Your computer simply does not meet the minimum hardware specs for the Adobe Flash player according to http://www.adobe.com/products/flashp...ech-specs.html
Flash is a proprietary, closed-source product of AdobeCorp, so there is really nothing Ubuntu developers can do to modify or improve it.
•2.33GHz or faster x86-compatible processor, or Intel Atom 1.6GHz or faster processor for netbooks
•Red Hat® Enterprise Linux® (RHEL) 5.6 or later (32 bit and 64 bit), openSUSE® 11.3 or later (32 bit and 64 bit), or Ubuntu 10.04 or later (32 bit and 64 bit)
•Mozilla Firefox 17 or Google Chrome
•512MB of RAM; 128MB of graphics memory
My suggestion would be to download the video to your hard drive and then watch it with your favorite video player app. (My personal favorite for low-spec machiens is mplayer.)
I'm sorry but I am not familiar with your sound card.