The videoflip element doesn't handle all formats, so some formats like
Intel Indeo 3 will cause errors and fail.

Add videoconvert before videoflip to do format conversion when it's
needed.
Signed-off-by: Jan Schmidt <jan@centricular.com>
Signed-off-by: Andrew Eikum <aeikum@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>