Assuming only a partial license number is attainable, I would say that for it to pass the worthwhile test you’d first have to narrow down and – if possible – ID the make, year, and color of the vehicle.
It looks like it’s an out of focus situation (or weak camera auto-focus function) hampering the necessary visibility even though enough information might be there. At the outside chance the movie file was emailed over, you would want to get hold of the raw files on a disc without compression since as you know as the raw files will have the most information possible in each frame to begin with.
It would be helpful to get the technical details of the camera, especially its frame rate and number of pixels information in PPI (not DPI) to make a measurable assessment about image information capacity.
Isolate the frames of interest (it looks to be around 15 FPS or so and if it’s a totally wireless camera setup I’m assuming a 5Mbps average bandwidth).
Import a frame at a time into Photoshop as a separate layer using a 4K monitor.
Image conversion options will lose some information but is worth a try later, however before trying that find the optimum sharpening, zoom-in, contrast – even inversion – for each color and B&W photo. Zoom until pixelation occurs.
Take note of each image’s object of interest in its sizing, in this case the license plate.
Try grouping different combinations of similar size images by turning on and off the images as layers and try to get a partial license number. Try grouping B&W with color as the last resort. If nothing, the last attempt is to try the many photoshop image conversion options (Rasterize, RGB, etc, etc) and repeat the sharpening/contrast process after that.
Turn over any single or multiple set of numbers discovered to the police to work with in the state’s DMV database for matching up to that type of vehicle.