Inserting YouTube Player into a site with changes: how difficult and what about copyright?

Question

YouTube

I'm wondering how difficult it is to embed YouTube Player on a site with a speed bound to 1.25 and the ability to upload audio for processing without uploading directly to YouTube servers, i.e. tear out the player itself and not use the server part of user data processing.
As it appears: the user on the site selects an audio file from local storage, the server converts to 1.25 (using YouTube or VCL player technology, no pitch increase, only bitrate) speed and displays.
Just tell me which way to look, because the YouTube API did not find an answer to this question.

Answer 1

what about the meaning? what KVS or analogues do not fit?