The video you are looking at is no doubt for replacing a cartridge bearing where you would need to ID the bearing if you need to replace them. Yours is not a cartridge type bearing, but caged loose bearings. Unless there is some issue such as gouged race or cone surfaces, just remove as much of the old grease as you can with some solvent, re-grease and put it back together. Just make sure you don't mix up the bearings as they might be different and remember the top and bottom orientation of the bearing cages so you don't put one or both in upside down. BTW generally there is no reason to replace the bearings unless they have been run dry, or look rusted or pitted.