preview seek examples (created with ffmpeg and ImageMagick)

Player supports Thumbnail Sprites; multiple thumbnails stitched together into a single image. 

In the VTT file, the individual thumbnails can be identified by appending their coordinates to the thumbnail URL using a spatial Media Fragment, for example:

Player only supports pixel-based fragments, not percentage-based ones.

WEBVTT

00:00:00.000 --> 00:00:05.000
data/seek/01_seek.png#xywh=0,0,120,68

00:00:05.000 --> 00:00:10.000
data/seek/01_seek.png#xywh=120,0,120,68

00:00:10.000 --> 00:00:15.000
data/seek/01_seek.png#xywh=0,68,120,68

00:00:15.000 --> 00:00:20.000
data/seek/01_seek.png#xywh=120,68,120,68



VTT files are subject to cross-domain security restrictions and therefore won't automatically load from another domain than the player.