The problem with Mallett's theory (the one in the videos) is that it depends on the existence of a 'line source', a 2-dimensional singularity, basically a linear black hole. This places his theory roughly in the realm of fairy dust and flying monkeys, unless John Titor shows up again.
Hydro, check out the [link=http://www.npl.washington.edu/ti/]Transactional Interpretation of Quantum Mechanics[/link]... based on the stuff you've written I think you may have already read it, but if not you might enjoy it.
If you jiggle a particle, it pushes back. It does this as though it 'knows' exactly where it is in terms of the rest of the particles in the universe. But (according to Einstein) nothing can move faster than light, so if you think of whatever force is making the particle push back as being mediated by some (as yet undetectable) particle or wave, you'd expect to see the particle you pushed jiggle back not all at once, but at different times based on how long it took the perturbation to travel to other particles and bounce back at the speed of light. This clearly doesn't happen, and in various ways the different interpretations of quantum mechanics have tried to explain this away.
Cramer's theory holds that when you jiggle a particle, the perturbations travel both forwards and backwards in time (something Maxwell's equations DO permit). In the forward direction, the perturbation spreads out until it hits something that it reacts with, and the reaction bounces back in time. Since it travels the same distance in both directions, the backwards response arrives at exactly the right time to counteract your jiggling, and this also means that different particles at different distances will all contribute their responses at that exact time. The same process is happening in the other direction as well, with your particle sending a perturbation back in time where it causes forward responses, which also arrive just in time to counteract your jiggling.
Of course, this plays hell on the concept of 'free will' since it means that some portion of the universe's response to your jiggling has been traveling towards you from the far stars since long before you even existed.
The most interesting thing about Cramer's theory is that it doesn't change anything in quantum physics, it just explains it in a way that does away with some of the harder-to-digest parts of other interpretations (the whole 'observer collapsing a waveform' idea... what, a cat isn't qualified to observe whether it is alive or dead?). The forward and backward waves cancel each other out in areas of space-time that lie outside the classical path, and reinforce each other within that path.
If he's right, it means that we're living in a soup of interactions traveling backwards and forwards in time, but they cancel out so we only see the forward bits. Using this phenomenon for sending actual information back in time currently involves leaps of imagination similar to Mallett's line source, though... basically the idea is that in the future you create some absurdly powerful object that deforms space-time (more designer black holes?) and jiggle it, then detect the changes those jiggles made on particles in the past. You could do a sort of Morse code by moving the fanciful source in and out of line-of-sight of the target, or coming up with some way to block its effects selectively.
And, since I'm on a ramble, an idea for people who reject the very concept of backwards time travel:
When you put on glasses with red lenses, you see everything in red. If they were blue, you'd see everything in blue. With or without those glasses, the process of 'seeing' implies that photons have interacted with your eyes (interesting side-effect: this means that if you were invisible, you wouldn't be able to see anything), triggering an electrical cascade that gets sent down your optic nerve to your brain. That whole process is entropic: complex molecules break down into less complex molecules, stored energy is released, the amount of energy in your body goes down... and all of that happens in a framework where you eat to preserve yourself, but that takes away energy from plants and animals, which in turn take away energy from the earth, which takes away energy from the sun, etcetera etcetera... the whole thing is winding down, every step in the whole process is governed by entropy.
Perhaps we see everything though entropy-colored lenses.
Since entropy is a one-way process, our entropic seeing process might only allow us to see other entropic processes, the way polarized lenses only let you see light that is similarly polarized. There could be all kinds of things going on around us that we simply aren't able to perceive since all of our tools for seeing are entropic.
Just an idea.