Added 4k videos + error handling for invalid video source

[jonathonwpowell]

I added the ability to use the 4K videos through a button on the new Video Source tab. It links to a json document I am hosting, as the new JSON is in the incorrect format and this would be the easiest way for now and I couldn't think of a more elegant way. If you have any ideas for doing it better, let me know

[joerchnet]

Some dirty hacks to get 4k videos work without compiling (this is my first write on github, so keep cool):

• install k-lite codec pack (to enable HEVC decoding with Windows media player)
• do not install "extra offer" during installation process
  https://codecguide.com/download_kl.htm
• grab the 1.6 screensaver release from here: https://github.com/cDima/Aerial/releases/download/v6.1/Aerial.zip
• extract to disk
• right click on AerialScreenSaverV6.1.scr and choose "install"
• go to control panel screensaver, choose AerialScreenSaverV6 from list, click settings and click "cache
  videos"
• enter cache location path (need space for 10+GB)
• let aerial run, the videos will be downloaded into cache location
• force it and download all low-res aerials mov from here to cache location
  https://s1.mzstatic.com/us/r1000/000/Features/atv/AutumnResources/videos/entries.json
• download 4k versions from here
  https://sylvan.apple.com/Aerials/2x/entries.json
  ISS: http://benjaminmayo.co.uk/scripts/apple-tv-screensavers.json
  you need all 4K_SDR
• overwrite all *comp.. for instance comp_LA_A006_C008_t9_6M_HB_tag0.mov with 4k version
  LA_A006_C008_4K_SDR_HEVC.mov (rename it)
• feel fine!

[Simsz]

@joerchnet I'm understanding what you're doing for the most part but you're just renaming the files and deleting the old SD ones so that you can replace them with the renamed 4K ones correct? I'm trying to get the ISS aerials to work and I seem to be doing something wrong is all.

[joerchnet]

@Simsz Try the following:
Aerial uses Windows media player for playing, no 4k capabilities out of the box. Try if the movie plays with media player. If not, install k-lite codec pack. If file plays fine with media player, disable the "use time of day" option in aerial settings.

[rarspace01]

What's missing/needs to be done to get this PR merged?