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YouTube videos are skipping to the end for users with adblockers
(9to5google.com)
This is a most excellent place for technology news and articles.
I don't have exact numbers, (just anecdotals) but SponsorBlock has some basic stats, and so far they've saved people over 3962 years worth of time. By dividing that by how many skips there are, (3,608,826,265) you get roughly 34.6452092 seconds. Per skipped segment, which videos often have multiple of.
This doesn't include videos that are purely promotional sponsored videos disguised as content, (see modern LTT or RyanToyReviews) video content that would break the coherency of the video if skipped or actual non-video ads that are becoming more and more frequent.
SponsorBlock also has options to skip filler in videos, which is hit or miss since it's all community submitted, but..