Not really putting any stock in them either, until we get more info, but...
Freeza worshiped Birusu and there's a flashback of young Vegeta where Freeza tells him stories of the God of destruction.
The Freeza worshiping thing has come up in a few other predictions so far, but the more I think about it...I dunno. I just don't see it. I find it more likely that Freeza claimed to have killed Bils after he disappeared, and therefore amped up his own reputation, because everyone knew that Bils was strong...just no clue how strong he really was, obviously. I could see a flashback of young Vegeta being present for that little story though.
Birusu attempts to destroy the Earth due to overuse of the Dragonballs.
I doubt it, but I would actually love this. One of the main things I like in GT is that the Dragons attack because of this, it's the perfect tie-in to Old Kai's complaints at the end of the manga.
Majin Buu and Gotenks die.
Hmm...it seems pretty unlikely, but maybe. I mean, we do know they summon the dragon for some reason in the film. Only thing is...Goten and Trunks are in that shot (can't remember on Buu), so...yeah.
Goku goes on an adventure to meet the God of creation to help defeat Birusu while the rest battle him on Earth.
Not an 'Adventure' maybe, but I could see this happening possibly. And count me among the people who would
love if it was Toribot. Voiced by Toriyama himself no less.
Videl ruins Pilaf's plans for world domination.
This is entirely possible, and could work with her 'big involvement' maybe.