Disclaimer:
This video's main purpose is not to teach you new tricks, although it includes short instructions for some of these tricks in case someone really wants to learn them. Instead it's just there to document and give a (hopefully) complete overview of all known tricks and glitches, which includes a lot useless but still interesting things too.

Also keep in mind that some of these namings might be inaccurate and that I had to make up a lot of these names myself.

Further notes:
This video has been in the making for a very long time now and I'm glad that it's finally finished now! While I can't say for sure that it really contains every little known thing in the game (I must have missed some things for sure), I can say that this is by far the most extensive collection out there.
This video contains a lot of different clips (almost 400), which I gathered from various Discord servers, YouTube, people sending me, my TASes or created them myself. Thanks to all the people that provided these clips.
Also thanks to all the people that helped in the process of making this video by correcting minor errors and listing things I should add to the video.

All the things listed in this video can be classified into one (or more) of three different categories:
-core-mechanic
-technique / trick
-glitch

For the purpose of this video I defined them in the following way:

core-mechanic:
A core-mechanic is any single action the player can do ingame that is directly built into the game and intended by the developers. This includes jumping, grappling and sliding for example. I omitted most core-mechanics as they should already be well-known to most beginners and I felt that adding them wouldn't add any value.

technique / trick:
A technique or trick is any action or sequence of actions the player can do, possibly in a specific situation, that is not a core-mechanic and can be used to their advantage. A technique is often times a combination of multiple core-mechanics and/or exploits certain aspects of the game's physics and/or glitches. A technique will in most cases not be intended by the developers but they don't necessarily have to be a glitch (e.g. spam grappling). In order to further distinguish a technique from a strat, a technique should not require the map to be built in a very specific way and therefore be more universally applicable than strats which are mostly bound to only a single map.

glitch:
A glitch is an oversight in the game's code or design, causing unwanted behavior to be possible. Most glitches presented here do not have any use and are just added for the sake of completeness.

Note that some things might be a technique/trick and glitch at the same time.

I haven't actually provided any classification for the things presented in the video but it should be possible. Except for splitting everything up into 4 levels, I also haven't really put these things into any order.
These 4 levels are mostly based off of how well known a specific thing is, but they might also relate to how weird/obscure it is (which is pretty much subjective).