Midori asks for H.264-Codec on Youtube and crashes.

A window pops up when visiting a Youtube-page. As soon as I click CLOSE the whole Browser crashes.

ProblemType: Bug
DistroRelease: elementary OS 0.3
Package: elementary-desktop 1.348+392~ubuntu0.3.1 [origin: unknown]
ProcVersionSignature: Ubuntu 3.13.0-32.57-generic 3.13.11.4
Uname: Linux 3.13.0-32-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.3
Architecture: amd64
CasperVersion: 1.340+elementary3~ubuntu14.04.1
CrashDB: elementary_meta
CurrentDesktop: Pantheon
Date: Wed Aug 27 15:00:06 2014
LiveMediaBuild: elementary OS 0.3 "Freya" - Daily amd64 (20140810)
ProcEnviron:
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: elementary-meta
SuspiciousXErrors:

ThirdParty: True
UpgradeStatus: No upgrade log present (probably fresh install)