Ok, given the confusion above I’ve closed this thread and stickied a new one with correct information and 2 options, the simple all in one “Mega” pack and the alternative install 2 or 3 codecs and decoder separately.
https://www.benchmarksims.org/forum/showthread.php?23687-Videos-not-playing-in-BMS-4-33
This should hopefully make it quicker and simpler for anyone new to this problem finding a solution.
Thank you to everyone who has helped, given feedback and confirmed what works.