Re: use of mediaplayer plugin
What browser are you using? If you are using Firefox, it may be the control setting: Tools > Options > Applications, then Check what "Adobe Acrobat Document" action is set to.
To view a pdf in Firefox see: http://support.mozilla.org/en-US/kb/view-pdf-files-firefox-without-downloading-them
And as to stripping the first "{", this is a Tiki, wiki parsed, forum, you can display the code with the CODE plugin:
{CODE()} {mediaplayer(...)} {CODE}
or use the "no processing" tag:
~np~ {mediaplayer(...)} ~/np~
Tom