BBB as a DVR

Sorry, if I am duplicating this, I think something went wrong when I tried to post it the first time. I was thinking that my BBB would be a good DVR (cheap, low energy consumption) but I am not sure where to start. Is there software like this that will work on AVRs?

https://en.wikipedia.org/wiki/MythTV

Would I be able to use one of these on a BBB?

https://www.amazon.com/HAUPPAUGE-WinTV-DualHD-Tuner-Windows-1595/dp/B015IL0FIW/ref=s9_simh_gw_g147_i1_r?_encoding=UTF8&fpl=fresh&pf_rd_m=ATVPDKIKX0DER&pf_rd_s=&pf_rd_r=D40PCZDCWSDE10Q9XK55&pf_rd_t=36701&pf_rd_p=a6aaf593-1ba4-4f4e-bdcc-0febe090b8ed&pf_rd_i=desktop

Could I connect an external hard drive through my