HiDef Media Player is considered by many users to be an adware application that not only installs ads in your browser, but also annoys you with pop-ups, search results, in-page linked works, etc. The playback problem can also be related to the codecs it's using. Install a new set of codecs using the application's page at Software Informer. Download Combined Community Codec Pack, install it and try a new playback of the videos you have.
