This site uses owned CDN to speed up the video and mainly use MP4 format. After 2016, this site also supports WebM format.
Use qHD (540p) standard HD. Both H.264 and AAC in MP4 package and VP9 + Vorbis in WebM package use approximately the same bitrate for each format of each video, and usually the latter is of higher picture quality. The site for 30 frames of video using the average rate of 1000kbps, 60 frames of video using the average rate of 1500kbps; audio is mono 64kbps bit rate. Usually, the site's video (no matter what format) on the screen at 720p or lower resolution are very clear (for example, iPhone 6, this is only a subjective test). If the MP4 format is used under the screen of higher resolution, obvious signs of degradation of the image quality will be seen. WebM has obvious advantages.
Video：H.265 Multi-channel, CRF
Video：H.264 Multi-channel, average bitrate 1000k (60 frames, using 1500k), 540p quality, drop resolution using linear filters, multiple passes
Audio：AAC Mono, average bitrate 64k
Video: libvpx-VP9, the average bit rate 1000k (for 60 frames, use 1500k), 540p quality, twice passed