This indicates an attack attempt against a buffer-overflow vulnerability in ffdshow.
The vulnerability is caused by an error when the vulnerable software handles an overly long URL. It allows a remote attacker to execute arbitrary code via sending a crafted web page.
ffdshow (aka ffdshow-tryout) before SVN revision 2347
System Compromise: Remote attackers can gain control of vulnerable systems.
Update to ffdshow SVN at revision 2349.