Earlier quoted context omitted.
>Not sure if ublock can seek inside a youtube video. I was referring to a hashtag or simply a tag a piece of text that can be spotted and then that type of content skipped.
In videos with sponsors, YouTube adds a small notice when the video starts that says the video has sponsored content. It doesn't tell you where/when.
YouTube adds an overlay* in the upper left corner which says "Includes paid promotion". The overlay leads to https://support.google.com/youtube/answer/10588440
Also creator added "#sponosred" hashtag.
Both "Includes paid promotion" overlay* and "#sponsored" hashtag can be detected and therefore the video could've been skipped or hidden by some extension or by uBlock Origin filter. You can either rely on detecting aforementioned Google overlay* or sponsored hashtag.
*HTML code of "Includes paid promotion" overlay: