Video diagnostics

This browser's H.264/MP4 support: PROBABLY

A: faststart VSL (app host)

OK — metadata loaded, duration 194s, 1972x1080

B: original VSL copy (app host)

OK — metadata loaded, duration 194s, 1972x1080

C: known-good (app host)

OK — metadata loaded, duration 10s, 640x360

D: original VSL (external host)

OK — metadata loaded, duration 194s, 1972x1080