Hi
I can confirm that it works.
Today I uploaded a new bootloader to the old Mega with using Usbasp programmer and now the watchdog works fine XD
Edit: 30.12.2013 20:19
But I have question, it is possible to change the upload speed to the old value 57600, Now I have to used this:
mega.upload.speed=115200
I'm guessing that this speed is stored in the new bootloader, there is any easy way to change it ?