I would like to add one option to Jmeter you mentionned. You may also consider commercial tools like NeoLoad to load test your Video streaming applications (I am an engineer at Neotys, the software vendor of NeoLoad, a load testing tool since 2005).
NeoLoad automatically detects the video requests of a website, simulates client/media players and provides specific statistics related to the quality of the video playback. NeoLoad has advanced video streaming capacities so it will be able to stress your server to know how it behaves. Moreover, it will bring you dedicated metrics regarding the user-experience during the test thanks to various metrics such as Play Length, Buffer Fill, Lag Length, Lag Ratio, and Bitrate. More info at: neotys.com/product/video-quality-load-testing.html.
In addition, our WAN emulation capacity makes it possible for you to measure the impact of users using different network conditions (like 3G vs. DSL) on your server and on the user experience.
Please note you can download a free NeoLoad 30-day trial on our website. I'l! be glad to get your feedback!
Hervé Servy, Neotys Performance Engineer