With the old-style oil seals that had steel around their periphery you could do that. But not with the newer designs that have the rubber-ized OD. You watched the video yes, but what you didn't see was that he destroyed 6 seals off-camera trying to get 1 in right. You can't afford that.

Here's what I suggest...

1. Use a sharp blade (like a pocket knife) to chamfer the oil seal's entrance. That is, remove the sharp corner between the vertical and horizontal surfaces that's been left by the machining process. Just knocking off that sharp corner by 0.008" will help immensely. It doesn't take much.

2. Apply a very light coat of engine oil to the ID of the oil seal or shaft. 

3. Go on Amazon, MSC, or any other industrial supply source and order a small tube of "P80 Emulsion". This stuff is magic !! Wipe the seal mounting surface clean. Then use a cotton swab to apply P80 to both the outside mounting surface of the seal and the engine case. (It will look like skim milk and will appear that it doesn't evenly "wet" the rubber of the seal. It looks like it's doing nothing. This is normal.) But be ready ! Then you have about 30 seconds to push the seal into the case. And when I say "push" I mean use your 2 thumbs to fully seat the seal. No hammers. No punches. No strain. No struggle. 

If the seal's seat doesn't have a shoulder to stop the inward movement, your biggest concern will be inserting the oil seal too far (and thus possibly crooked) !! 3 or 4 drops of P80 is all it's going to take to install that $15 seal in seconds. 

Here's A Link to P80

Hope this helps.