I’ll make a quick hypothetical breakdown if I where to work on something like this. For the Vehicles and the Person id suggest buying the assets before as it would save tons of time and money. Going to go with 8 hour work days for simplicity sake.
Day 1 - Source textures, scene blockout, create asset list, model any assets we may not already have (bushes, street lamps, helmet), prepare and Import into UE4
Day 2 - Create Materials and apply to assets, Scene construction, plot out animation and camera matinee, begin animation work while referring to accident documentation.
Day 3 - Import animations and finish setting up any camera work. At this point I should have enough of the accident blocked out to refer to client with an update for accuracy or refer further into accident documentation. Finish animation and camera work, setup any lighting or touch up scene.
Day 4 - Finalize assets and animations if needed. Render out video, setup video software to re-encode or compress the video to something usable and transferable.
So about 32 hours give and take, probably quote a week for any complications that may arise. Now if the vehicles and the person weren’t pre purchased. I’d say about 2 or 3 days to model, texture the Person or even a day depending on the simplicity of the figure. The Car about half a day to a whole day. That motorcyle is really complicated so about 2-3 days as well, if you are looking for that level of realism.
That being said I am an artist and this is my perspective and my experience with the engine and zero programming experience.
Looking at the clip provided. It doesn’t seem like you’ll need any programming at all. Mostly animation and modeling if the assets aren’t pulled off the marketplace or other 3d store. Camera work and scene construction can be learned on the fly with video tutorials or Unreal’s documentation; implying you are not hiring anyone with Unreal Engine experience.
The only reason you would be using UE4 is to save yourself some render time since all this can be accomplished in any good 3D software. I guess that also depends how realistic you want it to look. While reflections are not real time, UE4 will provide you with quick realistic lighting and reflections almost instantly.