Strip ?si=, ?feature=, ?pp= and other tracking parameters. Keeps legit params (v, t, list, start).
?si= — share-source identifier (tells YT where shares came from)?feature= — referral feature attribution?pp= — playback parameters used for tracking?app= — app-source identifier&ab_channel= — sometimes added by YT for channel attribution&utm_source=, &utm_medium=, etc. — campaign tracking from third partiesref, src, utm or tracking?v= — the video ID (obviously)?t= or &t= — start-at-timestamp deep link (e.g. ?t=42)?start= — embed-style timestamp?list= — playlist ID?index= — position in playlist