VideoPlayer.cs: Don't throw an exception on metadata missmatch

Proton replaces video files that fail to decode with a blank.mkv, which does not match the dimensions of the xnb file, causing games to crash when trying to play said video.

This is technically a regression on wine-mono 9.2 to 9.3, as the check was introduced in commit bc669aac.

Instead, just do a warning log of the mismatch, and keep going with the theora metadata as it would in 9.2.