I'm using that amrestore command above, but it seems like amrestore only searches the first chunk of the dump: (indicated by the trailing .1)

backup@amandaserver:/tmp/restore$ amrestore -p /dev/nst0 hostname /foo/bar | tar xf - ./baz/alpha/charlie/foxtrot
amrestore: 1: restoring hostname._foo_bar.20071216.0.1
amrestore: 2: reached end of information
tar: ./baz/alpha/charlie/foxtrot: Not found in archive

It looks like amrestore is only searching the first chunk for /foo/bar.  I checked to see which chunk /foo/bar was on, and it looks like chunk 6:

backup@amandaserver:/tmp/restore$ amadmin Weekly info hostname /foo/bar 

Current info for hostname /foo/bar:
  Stats: dump rates (kps), Full:  9364.9,  -1.0,  -1.0
                    Incremental:   -1.0,  -1.0,  -1.0
          compressed size, Full:  77.7%,-100.0%,-100.0%
                    Incremental: -100.0%,-100.0%,-100.0%
  Dumps: lev datestmp  tape             file   origK   compK secs
          0  20071216  Weekly-01        6 118427450 92038617 9828