AntonQ said

I have limited bandwidth and data allowance, I need to be able to stop all videos downloading automatically. What I would prefer is that any video that tries to load no matter what player is stopped and that I am given the option to play if I wish.

I would set add-on, Flash player, to run when asked. And just allow this single time.

{ Ctrl + Shift + A } to open the Add-ons Manager tab, then click on Plugins. Look at each Plugin and on the right there is a "selector" box. Click "down arrow" and select Ask to Activate" to override "Always Activate" for every Plugin that plays video files. Then restart Firefox.