This is a more invasive change to the timecode indexer because ffmpeg removed the ability to to get the `pkt_pos` (byte location of a frame packet):
27f8c9b27b
As stated there, they don't think that using it too seek is any better than using the dts or the pts position of the packets.
While you can still seek with the byte position, you need to do quite a bit of extra work to get this information from ffmpeg.
As we are only using it for the indexer and only if the fileformat was quite old (mpegts etc) I thought that we could instead simplify this and always seek by the pts timestamp instead.
Pull Request: https://projects.blender.org/blender/blender/pulls/130444
4acb7455df