Comment by andix

Many things that used to be h.264 are now using h.265 (hevc). Without this license a lot of applications can't play hevc at all, they rely on the codecs included in windows (which are unavailable without a license). They either fall back to another codec, or stop working. The article mentioned issues with videos playback in browsers and issues with ms teams.

Applications like ffmpeg or VLC still work, but using them on a PC without a hevc license is probably illegal.