I was using the 32-bit version (with npwrapper). Today I tried switching to gnash. It doesn't work either. The log had some interesting errors (see sample below). I'm beginning to wonder if the problem is actually with the browser's Javascript interpreter - currently everything is enabled.
7980] 20:07:26: ACTIONSCRIPT ERROR: reference to unexisting variable 'com'
7980] 20:07:26: ACTIONSCRIPT ERROR: getMember called against a value that does not cast to an as_object: [undefined]
7980] 20:07:26: ACTIONSCRIPT ERROR: getMember called against a value that does not cast to an as_object: [undefined]
7980] 20:07:26: ACTIONSCRIPT ERROR: getMember called against a value that does not cast to an as_object: [undefined]
7980] 20:07:26: ACTIONSCRIPT ERROR: reference to unexisting variable 'com'
7980] 20:07:26: ACTIONSCRIPT ERROR: Reference to undefined member [string:google] of object [object(gnash:

bject_as_object):0x94a530]
7980] 20:07:26: ACTIONSCRIPT ERROR: Reference to undefined member [string:youtube] of object [object(gnash:

bject_as_object):0x94aa20]
7980] 20:07:26: ACTIONSCRIPT ERROR: Reference to undefined member [string:AbstractElement] of object [object(gnash:

bject_as_object):0x94aea0]
7980] 20:07:26: ACTIONSCRIPT ERROR: Reference to undefined member [string:ui] of object [object(gnash:

bject_as_object):0x94aea0]
7980] 20:07:26: ACTIONSCRIPT ERROR: getMember called against a value that does not cast to an as_object: [undefined]
7980] 20:07:26: ACTIONSCRIPT ERROR: Reference to undefined member [string:ui] of object [object(gnash:

bject_as_object):0x94aea0]