Time stamps

You use the timestamp by doing it like this:

"At 0:20, how does this mnemonic correlate to the sine, cosine, and tangent of the right triangle?" (not an official video just giving an example) the comment is asking the question about the mnemonic, and the mnemonic is stated at 0:20.

Basically to use a timestamp you say how much time elapsed in the video (minutes: seconds), which is used to refer to a specific part of a video or talk-through (this might not work ideally for other purposes).