Well, the "protects for up to two years" doesn't inspire confidence. It probably works for longer inside a frame though.
Also, it's worth mentioning that Weigel's frame saver (with is worth buying if you've never rustproofed a frame before, because it comes with detailed instructions on how to rustproof a bike) is the same stuff as Amsoil's Heavy Duty Metal Protector (HDMP) which is available at some hardware or auto-parts stores.
Finally, it's good that your frame is Hollow. Those solid-tubed steel frames can be rather heavy