These videos are in Adobe Flash Video Format (FLV) and can be played using any free FLV player such as the one from
http://www.applian.com/flvplayer/

Another very good compatible media player is Windows Media Player Classic.  It also plays file formats that the modern versions of Windows media player no longer play.

MPC is free and safe to install and will run on most versions of Windows:
•	Windows® XP Service Pack 3, 
•	Windows Vista, 7, 8, 8.1 and 10, both 32-bit (x86) and 64-bit (x64).
•	Windows 7, 8, 10.

MPC can be found at: https://mpc-hc.org/

Another trick to try on Windows is simply changing the file extension from FLV to MP4.