The video "did" it for me.
Sounds minor advanced to me during cranking.
Fire up sounds MECHANICAL to me big time!
I'd "base line" that!
Compression test FIRST!
I think you will "find" it there.
That sounds like valvetrain damage or a significant loss of compression backwards through the intake valves or escaping between the cylinder head and jug.
Tiny chance crossed SP wires could make that noise too. Check firing order carefully.
All of the other suggestions regarding distributor indexing have been fine.
One thing that no one has suggested is using the compression pulse to verify if you're at TDC compression or TDC exhaust.
Most engines are a PIA to remove the valve cover to check, the type 4 is easy.
I NEVER remove the valve cover...
You can remove the check valve from the compression tester hose and screw it in the spark plug hole. You now have nothing more than a tube into the cylinder.
On everything except a completely destroyed motor you can rotate the engine by hand (or tire-that's easier on a type4) putting your thumb over the open tube and when you reach the compression stroke you can feel the pressure. Even slow rotation speed will end up blowing your thumb off the tube. It will be obvious!
Rotate up to TDC and you're TDC compression.
I'd check compression first, if fine leave all the plugs out and verify TDC compression using either my method or
@cgnj . His is fine too-his will verify TDC compression on a trashed motor where mine will not.
As I would employ a "bump starter lead" mine can be done very quickly.
His requires removing a valve cover.
Adjusting the valves is a common maintenance item that I'd want to do anyway.
I just wouldn't want to do it to a motor that requires removal for repair.
Setting dwell with a dwell meter is a requirement, not an option. You can see dwell on a meter during cranking alone, engine doesn't have to be running.
No-ones suggested checking spark intensity. I'd hold the coil wire 1/4-1/2" away from the case. Personally, I'd kill fuel during this. Have someone turn key to start while watching spark intensity. Should be little blue lightning bolts, sharp electrical crackling noise.
Should look and sound a bit like a stun gun...
I suggest insulated pliers.
Hope this helps!
I'd do a compression test first.