According to his website  for this, he says that "TLD has been tested using standard hardware: webcam, Intel Core 2 Duo CPU 2.4 GHz, 2 GB RAM, no GPU processing is used and runs in a single thread. The demands of the algorithm depend on required accuracy of the algorithm. Implementation for mobile devices is feasible." in response to "What kind of hardware it was running on?"
So, according to him, it is lightweight enough to run on mobile devices. I'd imagine there are also several optimizations that can be done (leveraging multi-core chips or GPUs, for instance) to make the performance significantly better than the prototype he's demonstrating now. Also, taking into account Moore's Law, we may not be able to run this on today's mobile devices, but surely could on tomorrow's. Given that research is generally a few years ahead of industry, I would expect that, by the time this would come to market, the devices will be more than capable.