there are all sorts of line stunts. some as basic as slanting right or left, or pinching to the inside. The stunt Gruden referred to was the T-E stunt, where the DE allows the DT to crash out to the OT, and then the DE loops inside and attacks the "B" gap which is normally the gap the DT is responsible for. SF has always been very good at it, with Justin Smith being a master at "holding' up the OT while the OLB loops inside. This is very effective in passing downs, but a high risk tactic against the run.
Which is why, IMO, the Rams just don't use them as often as other teams. If you get caught in a DL stunt, you are sacrificing gap integrity, and can get gashed for big runs. With the issues they have had in stopping the run, I am fine with them NOT over doing the line stunts. If you can force teams into throwing situations, then by all means. But against the likes of SF, and Seattle, you just aren't gonna make them a big part of the game plan.