It's actually quiet hard to say what must be considered as a glitch and what is not a glitch in this game. Glitchless rules are kinda arbitrary but the thing is we can't modify them everyday because some people don't agree with it, otherwise this category won't make sense (I mean less than now :3 )

Some tricks aren't agreed by the whole community to be a glitch or not, as toad said. However, I haven't never seen someone saying that item climb isn't a glitch. Item climb uses the fact that you regrab an item while being midair, it's obviously not an intended mechanic. " All it is is bring an item close to you (with a feature the developer intended, grabbing) then jumping on it." Item climbing is climbing with an item, not jumping on it, you take it midair to jump on it.

It's easier to verify if the run was scripted with demos for exemple, you can't be sure at 100% with video only sometimes.

"if it shows the run from beginning to end" if you use the vault save th video doesn't show the run from beginning to end... The vault is a part of the run, so you have to submit with demos...