I wanted to know which V4 feature is affected by the red jumper, so I did some tests:

Feature -> Jumperposition
==========================
Sync on CRT -> open
PAL/NTSC screens on DIGITAL-VIDEO -> open & closed
6MB chipmem -> closed
SuperAGA -> open & closed
RTG (over DIGITAL-VIDEO) -> open & closed
16bit AHI device (over DIGITAL-VIDEO) -> open & closed
Paula Audio (over Cinch) -> open & closed
68080 with AMMX -> open & closed
Kickstart flashed to V4 -> open & closed
Motherboard kickstart -> Never
Mapping of kickstart -> open & closed
V4 IDE controller -> open & closed
AmigaDOS formated floppy support -> closed
Full floppy support -> open
Ethernet network -> open & closed
512 MB fastmem -> open & closed
microSD support -> open & closed
USB support -> open & closed
Parallel port -> open & closed (untestet)
Serial port -> open & closed

Hope that helps others.