100% longplay (or "101%", as the game likes to put it!). All bonus rooms and KONG letters are shown. With that said however, there is a bit of a weird glitch involving the KONG letters that happens a few times throughout this longplay. Basically what happens is this: I get a certain number of KONG letters, I collect three animal tokens, I play an animal mini-game and then get taken back to the main level. When I get the next KONG letter, the game acts like I didn't get the previous KONG letters that I got before the animal mini-game! This glitch isn't game-breaking or anything, but it may confuse some people. So if you see the game acting like I didn't collect certain KONG letters, rest assured that I actually did get them. You can rewind the video if you need to.
This was recorded on an emulator (snes9x) with a USB controller in one sitting; no save states or re-recording tools were used. I died a bunch of times during the recording, but the deaths have all been edited out, so none of them appear in the video.
Lastly, it's probably best that I explain what I did from 1:04:21 - 1:04:32. In the level Oil Drum Alley, in one of its bonus rooms you have to get three bananas, then a barrel will appear. You then have to use that barrel to break the right wall to enter a bonus room within a bonus room (!). To do it properly you need to grab the barrel as soon as you can, then hold right while jumping. This is kind of tricky to pull off if you don't know what you're doing, so I thought I'd bring mention to it in case it confuses anyone :)
Shoutout to my awesome friend Aidan for inspiring me to make this video. He has some terrific longplays on his channel, check it out!