The reason to expose an extension from my point of view is (a) to allow detection of support for uploading depth videos to WebGL and (b) to provide a single, efficient upload path that users can rely on.
3) The style of how to support the upload isn't very friendly to users because it requires manual conversion in the fragment shader. I'd much rather see float/half-float texture formats being satisfied, where the browser knows about the surface format of the depth texture, and converts it (on GPU, without blocking operation) to the specified floating point format for upload. This'd have the advantage of offering users a transparent support for depth images, regardless of their underlying format.Yes, with WebGL 1.0 the conversion is a little painful. This will become trivial with WebGL 2.0 and the availability of R16UI / R16I textures. I'd like to focus on getting WebGL 2.0 out the door, but we'd appreciate any concrete suggestions you have for the Media Capture folks about better data upload formats to use with WebGL 1.0.-Ken