Will not start

1973 P6 V8

This has been running fine and now will not start

There is a strong spark at the plugs and lots of fuel getting to the carbs. Both float bowls are filling up.

It did this before a few weeks ago and when it started it ran rough for a few minutes until it cleared up like this

A couple of days ago it started right up as i moved it out of the garage . When i went to put it back in it ran rough and now won't start
In a fairly tortuous and long video i found it will start with the throttle pushed to the floor

Then after a drive it idles and starts fine

I have a similar issue. Mine was in storage for a few months and was really rough to start and run, only firing on a few cylinders. I ended up getting it recovered to my house and the breakdown guy thought it was likely a stuck float in the passenger side carb (RHD).

I had a set of overhaul kits so replaced the floats and main jet, gaskets, seals etc, set the mixture jets to the recommended positions ready to tune once running, but it now point blank refuses to start! I have fuel in the carbs... I have a spark but not yet tested how good it is but I'm wondering if the electronic ignition is on its way out and not producing a stong or consistent spark, it started to play up before I put it in storage and this is the first chance I've had to spend time on it.
Jim, You say

I found it will start with the throttle pushed to the floor
Then after a drive it idles and starts fine

It sounds that starting from cold you may not have a rich enough mixture. The design of the cams on the carbs means that often when you pull the choke cable you get increased fixed throttle before the mixture cams start to do anything. Have a look at this. You may think you have the choke pulled out but it might not be increasing the petrol mixture.

Your comments would back this up. Also in your first video it seems to almost catch but not quite; then as you say it runs and starts fine when warmed up. I would look at the cold start choke mixture.