You shouldn’t have any problem downloading and transferring it to a flash drive as long as your hard drive isn’t FAT32 formatted (4GB file size limit). And the 1080p MKV (DNR or no) should play just fine from a flash drive on a Blu-Ray player.
Well, maybe. If connect directly to the TV I may not be able to change the settings anyway. Since my 4k TV is also a Roku TV, the remote is a Roku remote.