Yeh, for the second video all I did was put only the intro onto the timeline and rendered it as an uncompressed .avi, then converted to .mp4 just like the original video.
The same render settings were used and the intro alone seems to work fine, although playing the rendered .mp4 on my computer it turns out fine. It only seems to be when I upload the whole video (The first video) onto Youtube, the problem occurs.
I have tried uploading as .avi, .mp4 and .wmv with the same results. I’m sure I’m missing something.
I do have divx and also currently using the K-lite codec pack.