That CPU should have absolutely no trouble with streaming video. Even an AMD IGP should also not have any trouble, however a low-end card like a HD6450 may help with accelerated web pages, including Flash content.
More likely, the issue is with your Internet connection. If it's wireless, make sure you're using Wireless-N, not G or B. If it is wired, you may need to check with your ISP. If you haven't done it in a while, power cycle your modem and/or router. If you have wireless (even if your own connection is wired), make sure leeches aren't bogging down your connection; at the very least use WPA2 or MAC address filtering to keep them off.