On the 4th burn I'd rebooted my machine & cleared out space so the ISO wasn't fragmented on the harddrive, burn speed stayed steady but DVDDecryptor failed verify when it started to read back the 2nd layer
My portable DVD player handled the burnt disc fine, no pausing or stuttering when it reaches the 2nd layer because it's got an over-powerful laser and can play almost any disc you throw at it, but my main DVD player pauses for the layer change and then stutters badly during the next 10 mins of footage.
Then my burner started to refuse to read discs at anything other than 1x, didn't dare try burning anything with it in that state, so I got the unit out of my PC, took it apart and manually cleaned the laser head, put it back together and into the system and it read DVDs back at max speed.
Then I burnt disc no.5, it failed on verify at 53% which is a lot better than previous attempts because it meant it read through the layer change ok, so I tried it in my DVD player and it didn't pause or stutter at the layer change! but it still stuttered slightly a minute or two after but the player is old and the optical out started failing a few months ago (I think I need to clean the laser lens on that too), so I tried the disc on the player downstairs (exactly the same model but a year newer) and zero problems playing it on that one, you couldn't even tell there was a layer change and it didn't stutter for the 2nd half of the film at all.
Now burning disc 6 for DarkGruson
but will have to persuade someone else to post it, I'm still ill (stomach aches, headaches, usual feeling like death thing)