In the video Sodini, dressed in a white button-down shirt, is seen sitting in rapt attention, listening to author R. Don Steele tell the audience that men have to be tough to be successful in love.
"Nice guys must die," Steele said in the video. "I would say that is the problem with most guys in the room. You are too nice."
Sodini can even be seen with a young woman during a practice exercise during the seminar.
A copy of Steele's book, "How to Date Young Women: For Men over 35," was seen in a video tour of Sodini's house that he posted online.
Steele could not be reached for comment.
Sodini mentioned Steele's advice in another video he'd posted, identifying the author by his initials.
"RDS says that I have approximately, maybe 15 more years to be successful at this," he said.
But instead of continuing his pursuit of women, it is believed that Sodini calmly walked into the Bridgeville, Pa., LA Fitness Tuesday night and opened fire on a crowded Latin dance class. He killed three women and wounded several others before turning a second gun on himself.
The three who died were 46-year-old Heidi Obermier, 49-year-old Elizabeth Gannon and 39-year-old Jody Billingsley, according to the Allegheny coroner's office. Sodini also shot the pregnant class instructor, who saved her life and that of her unborn child by playing dead.
Funerals for the three women who died start Saturday.
Blog entries found online after Sodini's death indicate he longed for a relationship and was upset that he hadn't had sex since 1990. He also wrote of a troubled relationship with what he said was his domineering mother.
Steele's advice during the seminar seemed to speak to all those issues.
"It's normal to be scared when you've been hurt by women in the past," Steele told the group, including Sodini. "The first woman who hurts is your mother. And that lasts as lifetime."
George Sodini Posted Online Musings, Wanted to Meet Jesus
After the shooting, several Web sites, videos and blog entries came to the forefront showing that Sodini had been planning the attack for months, even "chickening out" twice, as he put it.
On one site, Sodini described himself as "Crazy George." That was in addition to the blog he apparently kept in the months leading up to Tuesday night's shootings at a suburban Pittsburgh gym, and videos he posted online.
On the "Crazy George" Web site, he says his age is "less than forty" and lists his marital status as "single bliss."
The site includes an "Interview with crazygeorge" in which he answers the question, "Have you ever been in love?"
"Hell yea, lots of times, I am still single so obviously nothing ever worked out," is the answer given.
If he could meet one person dead or alive, who would it be? "Jesus Christ."
His favorite alcoholic drink? "Don't drink."He also includes pictures of a cat named Snippers, whom he describes as "The Best Cat EVER!" Snippers, according to the site, lived from 1984 to 1999.
And he includes five "Dumb Blonde Jokes."
Most of the material on the site appears to be from 1999 and 2000. He turned to a blog in more recent times, and to videos he posted of himself online. The video was found by ABC's Pittsburgh affiliate WTAE.
"So my objective is to be real and to be emotional and to be able to emotionally connect with people," Sodini said in one of the videos. "It is easy for me to hide from my emotions for one day ... and there you go and one more day turns into one more year."
The videos were uncovered hours after a hidden message was found in the code of Sodini's blog that said he was considering calling off or postponing the shooting based on a woman he saw in a nearby park.
In another video, apparently posted in February 2008, Sodini gives a tour of his home, which featured a flat-screen television, computer and a dinner table set for two.
"The women will be really impressed. Come over here. There's reading material that we're all familiar with," Sodini says in the video. On the coffee table is a book titled "How to Date Young Women for Men Over 35."
In the video, Sodini discusses his tumultuous feelings for younger women.
"Because when I'm 10 to 20 years older than she is, she has to feel good about this thing and the only way around this is to work on this. ... I'm going to post this and see what comes back," Sodini said.
"Clearly, he has a problem because of what he did," forensic psychiatrist Dr. Barbara Ziv told "Good Morning America." "The frightening thing is, he is more like you and I than he is serial killers. He's not a guy who is killing because he enjoys killing. He's a guy who wants to make a mark. This is the only way he knows how to do it."
Police say Sodini used two 9-millimeter automatic pistols and fired 36 shots inside the class of around 30 women. He then used a .45 caliber revolver to take his own life. An unused .32 caliber semi-automatic pistol was later found in Sodini's pocket, police said.
"In our opinion, there was nobody in that club that could have done anything that could have prevented Sodini from committing this act," Allegheny County Police Superintendent Charles Moffatt said. "He was hell-bent. ... He just had a lot of hatred in him."
Sodini Left Notes, Circled Class on Calendar
Police found two typed notes in Sodini's bag at the scene, each reflecting his depression and frustration with women. He complained of "never having spent a weekend with a woman" -- a theme shared in chilling blog posts he is reported to have written.
Sodini entered the gym using his membership card around 11 a.m. Tuesday and then left, Moffatt said. He came back around 7:40 p.m. and left again. He returned at 7:56 p.m. and began shooting.
Sodini had apparently targeted the "Latin impact" dance class that was under way when he opened fire. "He had the class schedule with that class circled," Moffat said.
Sodini's Aug. 3 online diary entry, which included a date of death, was full of disturbing musings about religion and his plans for the attack. He noted that he hadn't had a drink since 2:30 on Friday as part of his preparation.
"Total effort needed. Tomorrow is the big day. Unfortunately I talked to my neighbor today, who is very positive and upbeat. I need to remain focused and absorbed COMPLETELY," the diary read. "Last time I tried this, in January, I chickened out."
The diary also indicated that Sodini hadn't had sex since 1990 and that his so-called "practice papers" -- details about the planning of the attack -- are welcome to be published afterward because "maybe all this will shed insight on why some people just cannot make things happen in their life, which can potentially benefit others.
"Maybe soon, I will see God and Jesus. At least that is what I was told. Eternal life does NOT depend on works. If it did, we will all be in hell," Sodini apparently wrote, before adding later, "I was reading the Bible and The Integrity of God beginning yesterday, because soon I will see them."
One of the survivors, Mary Primus, was the aerobics class instructor and was 10 weeks pregnant. The class on Tuesday was supposed to be her last session. Primus was shot twice, once in the shoulder, once in the back, and her husband, Alex, said she played dead to save her unborn child.
"It was scary to see her like that but it was good to see that she was awake and breathing right," Alex Primus said in the hospital.