User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:35.0) Gecko/20100101 Firefox/35.0 Build ID: 20141019004001 Steps to reproduce: 1. Force YouTube to use Flash rather than HTML5 (I used a User Agent editor to emulate FF32) 2. Open a new E10S window and load up a YouTube video Actual results: The page loads fine, and there are no errors logged to the Firefox console, but the player area remains blank. The plugin icon in the address bar shows up and indicates that flash is enabled and running. Expected results: The video should play as normal.

I started running into this this weekend as well.

I'm pretty sure this is bug 1082670 and isn't particularly e10s-specific. Do you experience Flash crashes in non-e10s mode?

I hadn't tested non-e10s in a while.. it's crashing as well.

For me, it works fine except in E10S mode, but it's possible that it's another issue. Loads of my addons are broken in E10S and one of those could be fixing it (don't know which one though - the only one that seems likely isn't the cause).

(In reply to jackwickham from comment #5) > For me, it works fine except in E10S mode, but it's possible that it's > another issue. Loads of my addons are broken in E10S and one of those could > be fixing it (don't know which one though - the only one that seems likely > isn't the cause). Could also be bug 961361, which is e10s specific.

With addons disabled, flash works with and without E10S, so it must be an addon issue rather than a flash issue.