Our major contribution is to propose QoE assessment methodologies for mobile YouTube which is currently the most prominent on-line video portal. For this purpose we designed two assessment methodologies which are reflecting real usage scenarios. The focus is given on different variables: the video streaming profile, end user device and overall conditions. Furthermore, the implementation of various test conditions into the test methodology is explained and both quality ratings are described in details. Finally, rating types are compared and their performance and contributions are discussed on selected YouTube QoE results.