First of all, it's lowercase {mp4}...{/mp4}. This is important.

Secondly, as long as accolade.mp4 is inside /images/video/ and "images/video" is set in the plugin's parameters, then your video should display just fine.

If you've double-checked the above and still see no video, it could be related to CSS conflicts. There's no reason for Admin Tools to block AllVideos...

Of course a URL to an actual page with the video on would really help me see what's wrong...

AllVideos is loading up just fine, however the path to the video file is wrong:

www.accoladeacademy.co.uk/images/videos/accolade.mp4 (404 error)

The video seems to be located in: www.accoladeacademy.co.uk/images/video/accolade.mp4

So you should ensure the path in AllVideos params is set to "images/video" and not "images/videos". In other words, you missed an extra "s".

Seems OK to me: jmp.sh/Ljuef8p

1. Any space you get top/bottom of the video is because it doesn't fit the player's 16:9 ratio. This can be adjusted by CSS. Since this has been discussed recently, see this: www.joomlaworks.net/forum/allvideos/54734-odd-margins-on-top-and-bottom-of-video

2. There is no reason for the player not to work, because it's the native one that comes with the browser. What you see is most likely browser cache. Re-test your site with a single private browser tab.