Yea, wiki.crazyengineers.com will be good
That will be really usefull for those pesky questions on seminar topics and collecting our tutorial list (which we should be increasing) and other specific things.
As for file hosting, Fileden would be good for all the files if it does not remove them automaticly after no-use of some months. Other option which we anyway will have would be our own CE server (where biggie has hosted this forum...i guess has a minimum of 5GB).
And for your screen casts, yea better to use something else then youtube. Also check Google vids(kinda larger size) if we have problems streaming live from Fileden.