Well I went back to official Videostream Chrome App (v2.15.522.1) today and everything working perfectly again, no problem whatsoever.

Thanks for this, "Videodream stream meme" working perfectly, like Videostream used to until first week of Feb 2015. Had tried everything that OP did, in addition added SONAR exception for NAV. Nothing fixed the loading, buffering and chromecast crashing problems with MKV files, particularly when audio switched to AC3.