n0nsensical

The broadcast flag specifies whether there are restrictions on the display and copying of programming. I'm not sure the exact details but Wikipedia says it requires "that all HDTV demodulators must 'listen' for the flag (or assume it to be present in all signals). Flagged content must be output only to 'protected outputs' (such as DVI and HDMI ports with HDCP encryption), or in degraded form through analog outputs or digital outputs with visual resolution of 720x480 pixels (EDTV) or less. Flagged content may be recorded only by 'authorized' methods, which may include tethering of recordings to a single device."

As a purely technological measure, it's not much since any device could simply ignore the flag; the problem comes in when the government makes it illegal to sell or distribute one that does. The FCC already tried to do that, but last year the DC Circuit Court of Appeals ruled that the FCC didn't have the authority. Ever since, the usual suspects have been trying to convince Congress to pass a law enforcing the flag or giving the FCC authority to do so, and nearly succeeding. Fortunately even if that happens, devices currently in use that are unaware of the flag will continue to work. Also it only applies to over-the-air broadcasts. Cable companies can do whatever they want and I think it's pretty standard for them to heavily encrypt HDTV programming such that only their box can decode it anyway.