You are breaking several of YouTube's TOS (
https://www.youtube.com/static?template=terms)
> (5A) you agree not to distribute any part of or parts of the Website or the Service, including but not limited to any Content
By downloading and sending the videos from your servers, you are distributing their content.
> (5C) you agree not to access Content through any technology or means other than the video playback pages of the Website itself, the YouTube Player, or such other means as YouTube may explicitly designate for this purpose
Downloading a video via CLI is not using the YouTube player.
> (5D) you agree not to (or attempt to) circumvent, disable or otherwise interfere with any security related features of the Service or features that (i) prevent or restrict use or copying of Content or (ii) enforce limitations on use of the Service or the content accessible via the Service
By removing ads you are interfering with the restriction that users must watch ads.
> (5L) [...] not intended to be downloaded (either permanently or temporarily), copied, stored, or redistributed by the user.
Should be obvious.
> (5M) You shall not copy, reproduce, distribute, transmit, broadcast, display, sell, license, or otherwise exploit any Content
You are copying and distributing the content.
