Here’s a stereoscopic demo showing how I’m bookmarking 3D YouTube videos for the VRTube app (the VRTube link has been added to my video description below).
Watch this video in 2D or stereoscopic 3D by selecting the viewing options in “Settings” (if available in your YouTube video player).
VRTube Preview – A YouTube 3D video player for Android: https://play.google.com/store/apps/details?id=com.ideamats.vrtube
3DTube – A YouTube 3D video player for iPhones, iPods and iPads: https://itunes.apple.com/us/app/3dtube-youtube-3d-video-player/id594614158?mt=8
You can also download a YouTube video with your favorite YouTube video downloader, then use a freeware media player with stereoscopic 3D and 2D viewing options:
…or you might have a media player that you prefer.