Here are some great freebies for football, basketball, or baseball fans interested in watching old, classic games. First up free NFL Gamepass until 5/31/20. You'll gain access to full broadcast replays, condensed games in ~45 minutes, and the all-22 coaches film. I listed this one first because the NFL is giving access to games from 2009-2019!
NBA League Pass is also free until 4/22/20. This provides full length and condensed replays of all games from the 2019-20 season, as well as an expanded archive of classic games.
Finally, MLB TV has opened their recent archives and will let you stream any game from the past two season. With over 4,800 games, you'll have just enough time to watch them all 5 times each before our quarantine is over!