Overhauling 1998 Campagnolo Chorus Ergolevers
I have managed to overhaul early 2000s Veloce and Mirage, which have the exact same mechanism down to spare part codes, using only the exploded view from the spare parts catalog.

The exploded view looks like an explosion of small parts, but in reality the parts can all be removed and added one at a time, like in the UltraShift video. The mechanisms work on similar principle, the main difference is that the Ergo is disassembled only from the back. If you are only overhauling the index mechanism, you don't need to remove the brake lever. Instead, you pull it back and it exposes a large hex head. Insert a hex key here and it supports the axle (EC-CH135) while you disassemble the rest. For replacing the downshift return spring (EC-RE137) you need to remove the brake lever.

No video, sorry.