1996
YouTube's plan backfires, people are installing better ad blockers
(www.androidauthority.com)
This is a most excellent place for technology news and articles.
Read point 3 again. Regulations require companies to visually distinguish between ads and non-ads. That's why u get the yellow box with "ad" written in it, which indicates that the video that u r watching currently is an ad.
Software could thus use this factor very easily by scanning the stream for such an indicator. The moment it finds something like this, it skips to a frame where this indicator isn't present.