Complex sentence: These effects were in large part performed with the help of the native Amiga graphics chipset which were synchronized to the NTSC video signals; the result being that while the Toaster was rendering a switching animation the computer desktop display would not be visible.
Split into simpler sentences: These effects were in large part performed with the help of the native Amiga graphics chipset, which would be synchronized to the NTSC video signals. As a result, while the Toaster was rendering a switching animation, the computer desktop display would not be visible.