Android natively supports various video codecs including MPEG-4 SP, H.264 AVC, and H.263. However, your stock Android video player app might not run HEVC files and several other formats if it's old.
There’s no shortage of off-the-shelf (OTS) video players to deliver content online. Enter the term “video player” on the popular GitHub code repository site and you’ll see more than 1,000 results.