Maybe a little late to the game: BLINK
So a question has been brought to my attention after rewatching the series 3 episode BLINK. A giant plot hole, as I see it. Unless, that is, I'm just missing something fundamental and will feel incredibly silly after having the answer explained to me.
So the Doctor makes the recording that Sally Sparrow, which she will see on her DVD's. DI Shipton will put that recording on those DVD's. All this is well and good. However, the Doctor records that video in 1969. DVD's won't be around until the 1990's. Billy will have no way of putting that message on the discs for another 20 or so years! The Doctor even apologizes to Shipton when he warns him that getting the message to Sally is going to take him "a while". Do the Doctor and Martha just STAY living life on the slow path for that whole time? Martha, obviously, isn't noticeably aged after this adventure.
The only thing I can think of is a rather horrifying situation similar to what happened to Amy in THE GIRL WHO WAITED. The only possible scenario I can come up with is that Martha and the Doctor DID live on the slow path for 20 years. But when the TARDIS was sent back, it interrupted their time stream, allowing them to negate the years they had lived as though they had never happened. By stepping into the TARDIS in their past (a deviation that that didn't encounter initially), they were able to cause that specific future to never happen.
Then again, I could be missing something. Maybe I'm overthinking it?
I'm wondering if this is just a case of: