It sounds like you recorded in a high resolution, you can cut them into two separate videos and lower the quality. Maybe that will help. Also try other video formats. MP4 files are generally bigger than for example WMV files.

You are actually correct since it now takes more time because there are more matches in between it is impossible to beat the runs that were done before the Nations League were added. I think the best solution would be to make a new category for all the versions that have the Nations League. So you could still do runs on the old versions, where there is no Nations League. And on the new version, where there is the Nations League, people can still compete. But tell me what you guys think of the idea.