You've not told us which device you're using, Emmie. (Suggestions for a PC are likely to be useless for an iPad or Android device).
However if it's a PC, try uninstalling and reinstalling Adobe Flash:
Go to your list of installed programs (Start > Control Panel > Programs and Features) and uninstall any reference to Adobe Flash. (There will probably just be a single item in the list but it's just possible that you might see two or more).
RESTART YOUR COMPUTER (IMPORTANT!)
Then go here:
https://get.adobe.com/flashplayer/
DESELECT the 'optional offers'.
Click 'Install Now' to download the set-up file.
Run that file.
Cross your fingers and try the video again ;-)