Alternative hypothesis (assuming a bug rather than intended behavior): YouTube is testing a new ad mechanism, and the new mechanism (rather naturally) wasn't tested on systems blocking ads; it then produces a delay if the ad can't be downloaded, rather than silently skipping it. But yeah, I do tend to watch most of my videos through youtube-dl these days, even though the HTML5 player works fine for me in Firefox with…
> videos through youtube-dl these days how do you find the video you want without using youtube? do you just use the youtube search interface then download the video by copying the url (w/o even clicking on the link to start the video buffer)
http://www.webupd8.org/2014/02/new-command-line-youtube-play...
incidentally, you could also just use google.