I set the flags to default, and after checking, it doesn’t appear that I have any addons that should be interfering. Also, hardware rendering is enabled. Still no dice. This happens on Youtube, Vimeo, etc. as well.
Dual-core Intel processor with Intel Ivybridge Mobile graphics, 4GB RAM, Xubuntu 14.10 64-bit.
Mesa 10.3, and Linux 3.17 kernel.