Upon selecting H.264 is the video export format within the properties panel Blender will immediately crash.
The same behavior has been exhibited across multiple machines, and by other users (https://plus.google.com/u/0/100086093708394633095/posts/3HxtdXmC3dw) The console reports the following information upon crashing:
*** stack smashing detected ***: blender terminated ======= Backtrace: ========= /usr/lib/libc.so.6(+0x7c70c)[0x7f118174970c] /usr/lib/libc.so.6(__fortify_fail+0x37)[0x7f11817f04b7] /usr/lib/libc.so.6(__fortify_fail+0x0)[0x7f11817f0480] blender[0x113dc41] blender(BKE_ffmpeg_property_add_string+0x116)[0x113dde6] blender[0x113dfa6] blender(BKE_ffmpeg_image_type_verify+0xa3)[0x113ff33] blender(RNA_property_enum_set+0x54)[0x1182234] blender(ui_but_value_set+0x250)[0xb1cd90] blender[0xb31aee] blender[0xb346ab] blender[0xb3ca5b] blender[0x94ef8d] blender[0x94f2b9] blender(wm_event_do_handlers+0x24d)[0x94f64d] blender(WM_main+0x20)[0x946470] blender(main+0x379)[0x9287d9] /usr/lib/libc.so.6(__libc_start_main+0xea)[0x7f11816ed4da] blender(_start+0x2a)[0x94264a] ======= Memory map: ======== ...
(Truncated. See full console crash log here: https://pastebin.com/SWup8RGj)