I recently started learning TASing, and, being a YI any% speed runner myself, have taken interest in improving Spezzafer's now vastly outdated run (both in terms of entertainment, and tricks).
New tricks: traditional wall jumping; spitting an enemy into the wall and bouncing on it; more 1-1 skips (2-1, 2-4, 3-1, and 4-7); arrow lift teleporting; and other basic route changes. I also tried to incorporate most of the other standard optimizations that were missing from Spezzafer's run (slope acceleration trick, hitting bottom of goal ring, pipe jumps, etc).
Yoshi's Island is a game with enormous potential for showing off, and as such, another reason why I've been interested in improving the old TAS was simply for entertainment value. Blame Trihex.
Unfortunately, due to the fact that this was my first TAS ever, there are a few areas where I learned how to better optimize something after the fact (such as running along the moving platforms in 1-8). Additionally, as I am only interested in entertainment value, there were a few areas where maximum speed was sacrificed to pull off various tricks (not interrupting a triple juggle, for instance, or being forced to pick up a star due to collecting a lot of red eggs). I am also uninterested in spending hundreds of hours retesting certain strategies that require large amounts of trial and error, in the interest of actually seeing a finished Yoshi's Island run (looking at you, Nxcy/Baxter! :PPPP)
By the end of world 2, it is approximately 5,000 frames ahead of Spezz's old run.
Hope everyone enjoys it, and huge thanks to Nxcy for teaching me basically everything I know. Many of the tricks (like walljumping over the 2-8 boss), and routes are thanks to Nxcy's brilliance, and he deserves credit for them.
World 1:
http://www.youtube.com/watch?v=VDCwIaGiY0I
World 2:
http://www.youtube.com/watch?v=ICSTWrm67UU
SMV:
http://dehacked.2y.net/microstorage.php/info/618251079/Carl_Sagan_Any_Percent.smv
Emulator: SNES9x 1.43 v17
ROM: Rom: Super Mario World 2 - Yoshi's Island (U) (M3) (V1.0) [!]