4K is here!
I'm filming in 4K now and most of the new clips are available in this resolution! These clips are twice as large as HD 1080 though, and XFM scripts set minimum prices on them automatically, so they're slightly overpriced, but I hope they're worth it if you want uncompromised quality and 3840x2160 resolution, which is exactly 4 times larger than current HD picture size!
Some technical details: these clips are encoded with modern x265 (HEVC) codec, designed as an industry standard for 4K content, with AAC sound in MP4 container. You will need to install h265/HEVC decoder or get one of many popular free media players on your PC to be able to watch them!
I recommend these:
Media Player Classic Home Cinema
Or get this codec pack:
Since 2015 all clips where model says more than a few words have embedded English softsubs in SRT format,
which should be displayed by default by any player capable of displaying subtitles (see the above links to recommended ones).