The problem I have with saying that we travel into the future by achieving a high percentage of the speed of light is not the same as controlled time travel. He says that it is the past that we wish to see, where I would much rather see the future. The problem is a matter of controlling time, or time travel. Relativity might play games with the image you will see, but will you actually have an extreme time dialation or will you just have the appearance of the ship be a matter of visual properties (thus discussed in Star Trek). I have a problem believing that a single timeline exists as to where time travel is only assured if it follows simplistic laws of light. That's just me, maybe.

On the Grandfather paradox:

This is exactly what prohibits us from time travelling to the past, acording to most reputated physical theories time travel into the future is perfectly possible, be it either in a primitive way, like achieving the speed of light or a rather big percentage of it and just allowing time to pass outside or through wormholes and space-time disruptions, either would be possible would we have the technology to achieve it.
On the other hand most theoretic physicists believe time travel into the past is impossible because it is unconsistent with electronic sum of historys (Feynman's theory) acording to this you wouldn't be able to change the past because it would clash with past reality, bearing in mind that the simple act of traveling to the past is changing the past, past time travel goes puff.