Any content on media servers or plugged in via USB can be accessed by switching on "VR Mode" in the Media Player's menu, but you can't just load up any old YouTube video and see it in glorious virtual reality. Only media that was "captured in equirectangular format by a 360-degree omnidirectional camera" and saved in a supported format can be viewed in VR. (For reference, that includes video files in MKV, AVI, MP4, MPEG2 PS, MPEG2 TS or AVCHD, as well as photos saved as JPEG, BMP or PNG.)
Sony also enhanced the Media Player's music capabilities, introducing support for FLAC audio and automatically upscaling lower-resolution files. Compressed MP3 or AAC files will get boosted to a quality approaching that of lossless FLAC or WAV formats thanks to the company's DSEE HX tech, previously available only in a handful of Sony's high-resolution audio products.