Wes' dream is indeed Sentai footage however the shots in which his Ranger-mates from the future end up appearing would be new footage.
Once you see the C-bots (my shorthand for Cyclobots) then that is when it goes back to new footage.
I'm not sure of the footage of the Time Ship coming out of its time hole and it landing but it does look like Sentai footage even though I don't recall a scene like that in Timeranger.
There's a scene in which Trip tries to get Nadira to help out a pregnant woman who has gone into labor.
The following shots of Frax in his Lab would be new footage. Even this shot of him being in the same shot as his Robot is new footage.
The shot of the Time Ship on the beach that Alex sees on his screen is new footage.
After Wes talks with his Dad, it then cuts to new footage of the Time Ship however I believe that was actually a recycled shot.
Here's a shot of the Frozen Mutants
Once you see Doomtron again then it's in new footage as these shots will tell you  
Once you see this shot is when it goes back to Sentai footage. This shot is a shot in which you see that shot and then the camera will zoom up so that you c an see all of the Robot's details.
There's a cut to Nadira before it cuts back to Sentai footage of Frax in Doomtron's cockpit. After he says Doomtron has been activated, there is then a cut to recycled American footage of Doomtron. However it then cuts back to the Sentai footage of Frax within the cockpit.
It looks like the next exterior shot of the Time Ship... that exterior shot appears to be Sentai footage.
All of the time holes opening.... all of that would be Sentai footage. However the shots of the civilians reacting to these strange time holes... the civilians would be new footage.
Once you see the Silver Guardian SUV then that is new footage.
This shot of Doomtron after it attacks a building currently I do not know whether it's Sentai or new. However now it looks more like new footage.
After Eric's morph sequence ends, it then starts back in Sentai footage with him calling for his zord.
These shots of Quantum  

are when it goes back to new footage.
This shot is likely Sentai footage.
However this shot of Quantum is when it goes back to new footage.
Quantum Ranger jumps up and then it cuts to a Sentai close-up of the Q-Rex Dino Mode's face/head.
More vortexes open up in Sentai footage. It then cuts to American footage due to the 5 unmorphed Rangers.
Another vortex opens up in Sentai footage before it cuts back to the American actors.
It then cuts back to more Sentai footage of the time vortexes sucking up the buildings.
Once you see an exterior shot of the Time Ship then it's American footage however I believe it's just a recycled stock shot.
Here's the insides of the Time Ship  
The shot of the red numbers that read "00:00:30" those numbers are new footage. Apparently they wanted to create their own countdown.
This shot is new footage.
This shot of the Time Ship Window is also new footage. I'm pretty sure about that 1.

Sentai footage comes from Time Episode 48