Yes, as said above, 1st upgrade would be SSD as an OS drive so that you have much shorter game loading and Win boot-up times. SSD also affects file read/write times and in general, SSD is 6x times faster than HDD. You can then keep your HDD as a storage drive.
If you want to improve your gaming performance, e.g high/ultra settings @ 1080p then 2nd upgrade would be GPU. GTX 1060 6GB would be more than enough for this. And thanks to the 550W Seasonic unit, you don't need to upgrade your PSU if you upgrade your GPU. Forcus+ 550 can even handle GTX 1070 Ti if needed be.
You can always upgrade your CPU too if needed, just make sure that your MoBo has the latest BIOS that supports Ryzen 2 CPUs. Best CPU you currently can upgrade to is R7 2700X,
R5 1600 vs R2 2700X comparison:
http://cpu.userbenchmark.com/Compare/AMD-Ryzen-5-1600-vs-AMD-Ryzen-7-2700X/3919vs3958
But since AMD plans to keep supporting AM4 socket for several years, your MoBo should also support future Ryzen 3 and Ryzen 4 CPUs. Oh, due to the B350 chipset, you can also OC your CPU if you need it. Just make sure your CPU temps doesn't go beyond reason.
For ideal video editing build, 32GB of RAM is best suited. And thanks to the MoBo i picked, you can easily upgrade your RAM amount to 32GB since MoBo has 4x RAM slots.