In addition to Oancitizen there were others who did April Fools Days jokes actually.originally posted by TnAdct1
Pretty much had a hunch that the fourth Anniversart event was currently being filmed, given the lack of April Fools videos by the TGWTG crew this year (with the only one that I'm aware of being done by Obscurus Lupa).
SciFiGuy did a review of Stardust in the guise of the Fantasy Guy.
Welshy did a list of the "top" Rose moments from Dr. Who that were really showing just how awful the character of Rose is. Truthfully you'd have to know Welshy and his tastes of Dr. Who to really get the joke but it still counts.
Angry Joe did a video about Guild's War 2 release which was really just a "psyche here's something random instead for 30 seconds" video.
Blockbuster Buster did a review of Sucker Punch in one of his alternate persona's and a 30 second one sentance review of Percy Jackson
And on his site (not on TGWTG or his blip page) Phelous did a review of the first episode of his old series Mortal Komedy.
In truth not really as good as some of the great pranks from last year but I think due to the anniversary filming being the week of April Fools that was the best that could be done at the time.