Firefox already supports H.264 videos, but unfortunately gstreamer0.10-ffmpeg on Ubuntu is an additional copyright restricted program, so it does not support H.264 videos. Therefore, you will install the Gstreamer ffmpeg plug-in to watch the H.264 video.
In this article, I suggest you download gstreamer0.10-ffmpeg *. They are installed through the gdebi deb package, but the gstreamer0.10-ffmpeg package can also be installed through some third-party PPA sources, so it is easy to install.
Download, install, and configure Ubuntu 14.04
Ubuntu 14.04 system:
Ubuntu 14.04 text tutorial on hard drive installation in Windows 7
Install FFMPEG on CentOS 5.6
WebRTC, H.264, and MP3 support are enabled by default in daily FireFox build versions.
By default, Firefox supports H.264, AAC, and MP3.
Firefox 20 supports H.264 video encoding and decoding standards
Mozilla will embrace H.264
Tiny6410 H.264 remote video monitoring practice
All you need to do is add the PPA to your system, update the local storage index, and install the gstreamero.10-ffmpeg package. Run the following command:
Sudo add-apt-repository ppa: mc3man/trusty-media
Sudo apt-get update
Sudo apt-get install gstreamer0.10-ffmpeg