One of the main reasons why third-party media players like Media Player Classic and VLC are extremely popular among Windows users is the proper subtitle support. A lot of folks watch videos in a foreign language, and having the option to easily attach a subtitle in their mother tongue, no matter the format it's made available in, is a must-have feature for many.
It would help if Windows Media Player or the built-in Video app, the latter of which is part of Windows 8 and newer versions of the OS, would meet their needs, but, so far, that hasn't been the case. However, Microsoft wants to change that with Windows 10.
According to the the software giant's Operating Systems Group's Data and Fundamentals Team general manager, Gabriel Aul, Windows 10 will ship with support for popular subtitle formats ASS, SRT and SSA, which use the unformatted UTF-8 encoding.
You might recognize SRT, as it's a popular format in which subtitles are offered for download from popular sources. ASS and SSA aren't as well known, but they're in fact commonly used for embedded subtitles.
Supporting ASS and SSA also means that Windows 10 (well, its built-in media players anyway) will recognize subtitles which are embedded in videos offered the popular format MKV, and not just DVDs or Blu-Rays. I believe it's not a coincidence that Windows 10 already supports MKV, which, as some of you may know, is a widely used format for videos shared, so to speak, via BitTorrent.
It's nice to see that Microsoft is actively trying to catch up, and willing to go the extra mile to make it easy for users to enjoy their videos. That said, I do wonder whether the software giant will promote these features, considering their connection to piracy. I suspect that the software giant is betting on word of mouth marketing to attract those using third-party media players.