Hi, I see some familiar names here.
The 28 minutes on TG is either a typo (ie, 48), or uses the warp glitch (I see that it's already been mentioned here). With the warp glitch, you can beat K Rool in under 30 mintues, with about 25% total (you'd skip pretty much all bonuses, but there's at least one in the misty mine that seems to help).
For 46 minutes (ZSNESed, lots of saves), I did make use of the warp glitch. There's 3 places you can warp (three bends in the dotted road to mash the button... you must have only 1 kong though, so you have to kill off Donkey). One of them leads to the middle of orangutan gang, not far from the expresso crate. In a 101% run you would reach up to orangutan gang so that you create the dotted path, but not enter it - you enter it via the warp and start about half way, saving a fair bit of time.
Anything under 50 minutes without saves is pretty crazy, nice work! Admittedly, I learnt a few tricks from Snap's 50 minute run.. one was a barrel in Barrel Cannon Canyon that I didn't know about (skips all those up-down barrels near the zingers, maybe 10 seconds worth). The other two were the locations of Enguarge in one of the water levels, and Enguarge in Poison Pond as well (perhaps another 10 seconds each).
For extra tricks, hmm.. what Derek did was pretty much all you can do. Of course, with save states you can use a lot of extra risky roll jumps, especially on those trick trak levels, and Platform perils.
Michael has just directed me to a newer version of snes9x that can rerecord from save states, making it possible to make a video. I'll probably give that a shot; I'm a newbie when it comes to making any form of movies (be it VHS or computer), but hopefully I'll manage.