There is some discussions about digital watermarking of copyrighted content folk are downloading from the internet. That is, a purposeful leak of a tainted, watermarked copyrighted work so that if folk are caught with such then it can be traced to its source.

Then again you may be creating your own MKV and need to re-examine your encoding choices.

More at

PS about the viewing angle. That's a known issue with all displays. Some are better than others and you should find your set at some store to compare.