Don't throw exception for missing Video until it's played

[redmcg]

This is a PR I originally raised against the wine-mono fork to fix an issue with Hell Yeah! Wrath of the Dead Rabbit (205230):
madewokherd#6

@madewokherd and I thought it would be worth checking to see if this was something wanted upstream.

The PR changes the behavior when a Video file is missing to match what Windows does. Windows will only throw an exception when you attempt to play the Video (rather than when loading the resource).

The aim of the patch is match Windows behavior, and therefore the focus is on the scenario where an XNB file is present. But as it is, this will also modify the behavior when:

• the XNB file is missing; and
• calls to FromUriEXT

which may not be desirable.

[flibitijibibo]

Interesting, so it's kind of like Song where it's really just metadata that gets ignored until VideoPlayer uses it... works for me, but I may have another way of doing this - will report back in a moment.

[flibitijibibo]

Did my own version of this - the main thing is that raw file behavior is preserved, which is what FNA games will prefer, but I redesigned the Video class in such a way that it acts more like Song, so VideoPlayer now does most of the work:

e86dbcc

Thanks for the PR, this was very useful information to have!

[flibitijibibo]

Actually woops, I forgot about the path normalizer - I'll apply this next.

[flibitijibibo]

65f98a8

[redmcg]

Thanks @flibitijibibo , can confirm merging this in to wine-mono FNA fixes the issue. 👍