As a general rule of thumb when working to a budget get the most powerful CPU you can afford balanced with money spent on I/O (input and output). I/Os in order of speed is CPU cache, RAM, SSD plus disk cache, then the hard disk platters. As video editing is CPU intensive, with a healthy amount of RAM, the amount of practical speed difference for SSD or hard disk I/O is less important, if important at all. Moreover note that video I/Os tend to be sequential rather than random.
Surface Pro (2017) vs Surface Pro 4