Mp4/h.264 videos(All websites) do not play properly on the LG G2 with KitKat 4.4.1 or 4.4.1. I have tried both the regular Firefox (32.0.3) and Beta(33.0), both seem to be having the issue. Playback works fine using mobile Chrome. Please also note, I am not using Flash player, these are standard html5 videos. Here is an example: http://www.quirksmode.org/html5/tests/video.html Screenshot of video(on device): http://postimg.org/image/enohww7nj/ WebM and Ogg/Theora play fine. about:support info: Application Basics Name: Fennec Version: 33.0 User Agent: Mozilla/5.0 (Android; Mobile; rv:33.0) Gecko/33.0 Firefox/33.0 Graphics Adapter Description Model: VS980 4G, Product: g2_vzw, Manufacturer: LGE, Hardware: g2, OpenGL: Qualcomm -- Adreno (TM) 330 -- OpenGL ES 3.0 V@66.0 AU@ (CL@) Device ID: Adreno (TM) 330 Driver Version: OpenGL ES 3.0 V@66.0 AU@ (CL@) GPU Accelerated Windows: 1/1 OpenGL (OMTC) Vendor ID: Qualcomm WebGL Renderer: Qualcomm -- Adreno (TM) 330 windowLayerManagerRemote: true AzureCanvasBackend: skia AzureContentBackend:cairo AzureFallbackCanvasBackend: none AzureSkiaAccelerated: 1 Important Modified Preferences Name Value browser.cache.disk.capacity: 204800 browser.cache.disk.smart_size.first_run: false browser.startup.homepage_override.mstone: 33.0 dom.mozApps.used: true extensions.lastAppVersion: 33.0 network.cookie.prefsMigrated: true plugin.importedState: true storage.vacuum.last.index: 0