[Mandrax]

The audio files are decently integrated, just omitted that part in log due to long text size.
The re-muxing experiment [mkv-->ts] gave twice, either doing it directly or via de-muxing first, .ts files which were only slightly larger than the .mkv files.
Having downloaded a .ts file some weeks ago about the size of 9GB I'm asking myself how much of that was really needed.
Being well aware that .ts files can bear quite some amount of useless data, size of it seems to be a function of recording software, this doesn't explain the drastic size reduction via the demux-mux route, or in other words how can a muxing process deliver a file size smaller than the sum of individual sizes.

So far I believed - and still hang on to it - that elementary streams are without extra overhead, but maybe that's the wrong part of thinking?

Additionally, have scanned quite some forums and the issue as such seems to be quite common, only answers found so far were all along the lines that .ts can have quite some overhead.

Having seen HD torrents here which were either .ts or .mkv so I still hope that some experts might provide deeper insight.