I think so..
I flew 747-100s and -200s at my first airline, then -400s at United. It's been 8 years since I flew the -400, but I think so.
At the first company, I watched a cockpit-video of a maintenance test-flight, in Tuscon, at about 10,000 ft. They needed to take it past redline and get the overspeed warning. Keep in mind,there is a warning for exceeding IAS, and also one for exceeding Mmo (Mach). The 10,000 ft check was for IAS warning.
As best I remember, IAS redline was 386 kts; Mmo was 0.92 Mach. I think that is true on all models.
I was amazed watching the video: they set takeoff power, and let it accelerate. Not only did it hit 400 kts IAS, the rate of acceleration at that speed made it look like it could have hit 450!! They terminated the speed run right as they hit 400 kts.
Now, to address the 700 MSL question: Probably. I won't go into the full explanation of the four significant types of drag, but for the same IAS, the drag is the same regardless of altitude or density altitude....except for Mach-wave drag. But if the 747 can hit 400 IAS at 10,000ft, then it should be able to at sea level...where the mach number is lower, and therefore, wave-drag is lower. (And the engines have even more thrust).
Not sure why the hosts were discussing a 747 and 9/11, since it wasn't involved.......