Wenn der Bach schmal genug ist, den Logger in einen wasserdichten Kunststoffbehälter tun, reinwerfen, nebenherlaufen und dann am Ende wieder rausholen. Behälter sollte für alle Fälle farblich auffällig sein sowie Hinweise für einen eventuellen Finder enthalten - man weiss ja nie...

In der Map den Data-Layer einblenden und beim Detail dann "show history". Dann siehst Du, wer wann an dem Objekt gearbeitet hat.

Hi! As far as I know, German law has always been that copyright need not to be explicitely stated. Since some 20 years, this also holds for countries like the U.S. Have a look at http://en.wikipedia.org/wiki/Copyright#Obtaining_and_enforcing_copyright

Sure a nice way to check and beef up the maps, but isn't it a copyright violation if we use such movies to check and tag OSM data?

Something to read:

osm.wiki/index.php/Proposed_features/House_numbers/Karlsruhe_Schema

As I pointed out, talk to the render guys about this problem. As said above, housenumbers may not be a vital information for map rendering, but for other applications of the osm-data.
Surely, proper rendering of house numbers isn't trivial. Maybe just render first and last numbers of houses in a block or something like this. Maybe you should put this issue into the osm forum http://forum.openstreetmap.org/

You don't map for the renderer. If some useful data isn't rendered nicely, it is a renderer's problem. Give the renderer guys a hint where to look at. But don't remove useful data from the database just because it isn't rendered nicely by one, some or all renderes.