[ksoza]

Can an SA 8300HD DVR (or similar) box from Comcast playback recorded programs without an active or working cable connection?

 

[demonfoo]

No, it won't.

 

[bfdtv]

If you want a DVR without a cable connection, take a look at:

1. TivoHD (dual-tuner)
   
   
2. Dish Network DTVPal DVR (dual-tuner)
   
   
3. Sony DHG-HDD250/500 (single-tuner, discontinued)