HD video packs - Tech Support

The error still sounds like a codec issue. The same thing happens with the original VOBs when the game is looking in the wrong place for an MPEG2 decoder. Originally the solution would have been to install something like mpeg2dec and run the 'register' function to make windows recognize it.

If you replace the original movie files does that make the game work again? If so I would recommend using something like the K-lite codec pack and then using the codec tweak tool that's included to adjust the directshow filters to handle VOBs and h264 files and whatnot.
when I install the WC4 5.0 Pack, All I get is a missing file notification and video playback error every time a video tries to load.
Hi @Sentry

Sorry for the very late response - I've been on a week's break and only just saw your query.

@AD's suggestion seems spot on (thank you for keeping the thread responsive, @AD! 😁). I believe VLC keeps the majority of its codecs to itself and doesn't install them system-wide for other apps to share. Installing the K-Lite Codec Pack will almost certainly resolve your issue. You can grab the latest versions here. I would recommend installing either the Full or Mega versions, since they also come with the Codec Tweak Tool and a couple of other applications which might come in handy if you continue to experience problems.