I was researching the crossovers for Fairly Odd Parents and came across on the FOP wiki an old Total Request Live episode which had an interview with the main cast.It said the clip of this is on the School's Out! DVD set, but I have yet to check.
What I found more intriguing was that there were other animated characters that popped up on the same episode. An archive for the show showed there was clips of interviews with Stewie Griffin, the Powerpuff Girls, Sly Cooper, and a call in from Peter Griffin. The only clip I could find online for this was a promo for the Sly Cooper clip on Vimeo.
I Found a Low Quality Screenshot of the Family Guy Portion of the Episode on a Old Family Guy Fan-Site on the Internet Archive while Trying to look for Something Else.
Sweet Revenge was a lost episode but it was found a while back, fairly odd parents was so mainstream it's probably somewhere, look for them on fan sites