Add Support for video playback

[Harry-Lees]

Issue

Add a preliminary support structure for video playback e.g. the ability to upload and play short GIF or MPEG files and similar. This merge does not have to be extensive and can be expanded upon later.

Ideal Features

• the ability to upload commonly used file formats.
• support for short (around 10 second) videos. Implementing longer videos is more difficult and is not a pressing issue.

Notes

The video_update branch has been closed due to merge conflicts with master. It contains most of the code for preliminary video support. This can be picked up and reworked to work with the current setup.