I have multiple youtube videos uploaded on the, now I want there be a marker if a particular youtube link is on for a particular time.
You could do a simple setup of setting a timeout for a function so that it runs after a set time. Then you could have that code either check the current play time of the video or if the video is playing and then do something if it is after a set time or is still playing etc.
https://www.wix.com/corvid/reference/$w.VideoPlayer.html#currentTime
https://www.wix.com/corvid/reference/$w.VideoPlayer.html#isPlaying
Previous forum posts that should help you.
https://www.wix.com/corvid/forum/community-discussion/timing-a-function-in-javascript
https://www.wix.com/corvid/forum/community-discussion/how-to-delay-going-to-a-link-after-clicking
https://www.wix.com/corvid/forum/corvid-tips-and-updates/give-the-textinput-onkeypress-function-some-time