I've only watched two sets of speed test videos between 2012 MBP and 2019 MBA and the 2019 MBA looks to be faster but not by much. I will say that I edit videos in iMovie every few days on my 2019 MBA and this machine handles it with ease. I also edit photos in GIMP, Affinity Designer and Affinity Photo and, again, this machine handles the workload with ease. I don't have a 2012 MBP to test with video or photo editing so I cannot comment there.
I had a 2017 MBP and was originally going to use a 2019 MBA to prove that the MBA was a low-end "junk" machine not good for much more than web browsing but I ended up being proven wrong. I went ahead and bought a base model 2019 MBA (1.6 GHz Dual-Core Intel Core i5, 8GB RAM, 128GB SSD) 4 months ago and I use it more than I use my 2017 MBP.. this little MBA is awesome.
I feel that you should stick with the MBP line if you plan to edit videos or large photo projects on a regular basis.. or you do a bit of coding. But, don't let the 2019 MBA specs fool you.. this little machine is fast and powerful.
You could always go to a store near you and test one for several days in a row.. that's what I did before I bought my MBA.