Hi,
I have the same problem. It used to work fine when I started using the Router 6 weeks ago but youtube stopped working after the Flash player upgrade on my PC (11.3.300.268, about 3 weeks ago) and on my Android phone (I don't have the present version). The weird part is that in Youtube you can see the thumbnails in the timebar (when I scroll the timeline button)

. I have tried other video streaming sites (Netfilx) and it works perfect. So, from what I can figure, the problem seams to be around the Flash Player after the latest upgrade. Anyone made the same observation?
I also live in Montreal and I my ISP is Videotron. My firmware is 1.02 on my DIR-835. Connected the router is a PC (wired), a laptop (Wi-FI), a IPod (Wi-Fi) and a Galaxy Nexus - Android 4.1.1 (Wi-Fi).
SirEnigma.