My thinking is how much could I regret $550 if I find it lags some? Then again on the other shoe, $400-$600 more to avoid that potential issue. I would honestly spend more to not have the issue. I am just seeing if there's a chance I won't.
Anyone know why the chromebooks are considerably cheaper than other laptops and 2-in-1's with similar specs?
For just "office" or playing vids and browsing type use 8gb should be good for awhile. You called it earlier with the SSD they really are worth it to speed up operating system and programs. They are good for speeding up an older system too but not a magic bullet as memory or even processor if its old enough can hold you back.
The only way you're going to get an SSD is if you buy a new computer with one installed on the mother board, and as far as watching videos, that depends greatly on your internet connection download speed. Cable is best. Even a slow computer can play video without digital lock up if it has a fast internet connection. Gaming is different, that requires RAM.
As long as you aren't doing demanding stuff like rendering or autocad or something a modern processor with 8gb memory and an SSD is going to be plenty fast for years.
As long as you have an available sata connection you can install a SSD. Laptop I would buy with it installed though taking those apart isn't easy.