My Samsung TV has apps and internet connection. One of the apps is ROVI TV listings. I checked the listings and in my NY local broadcast area the listings for ALL the local broadcast stations (must be close to 100 including substations although at my location I only get about 50) shows 7 days of guide data. So I would expect this DVR to provide 7 days if using ROVI. The guide is populated with ads though.
Tribune Media has guide data for about 90% of the channels in DFW, and the few that aren't listed are mostly infomercials and locally-originated programming, so it's certainly possible. OTA TVGoS wasn't nearly as complete, but perhaps they knew they were moving over to the Internet, and so never really gave the OTA service the attention it needed.
BTW, from watching DaveZatz's video, it appears the guide is a semi-transparent overlay of the bottom half of the screen, which leaves no place for ads. (I guess CM, E*, and Rovi worked something out to avoid ads.)
The length of Rovi's Internet guides appears to vary a great deal. Many devices reportedly show only 2-3 days; your Samsung shows 7; and the DVR+ is supposed to be 14. Probably depends on how much the manufacturer is willing to pay Rovi per unit to license their software and guide data.
Edited by JHBrandt - 12/26/13 at 1:16pm