Extend the list of raw video formats, and allow the playbin flags to be overridden by an environment variable when the default isn't suitable for whatever reason. Change-Id: I4c7d821b0ce29f5ad2dc0341e378ffd17c489e98 Reviewed-by: John Brooks <john.brooks@dereferenced.net> Reviewed-by: Yoann Lopes <yoann.lopes@digia.com>