Video encoding depending on its variances is mainly utilised by CPU and GPU performance, i believe hand-break specifically uses the CPU, therefore for your requirement the i5 is potential ever so more suited, however saying that the 13" core duo still stands quite a considerable level at doing such a job, ive converted a couple of videos myself and have seen such as significant increase in the speed compared to my previous Windows Laptop (Samsung R505) so if your wanting to save a bit of cash id recommend the 13", 8GB of RAM isnt really necessary unless you planning on running many applications at the same time that require extensive usage of memory, otherwise its pretty much unnecessary. Video encoding usually doesnt require much RAM so 8GB really would be unnecessary. In terms of the computer being 'University Friendly' either model is more than capable of both those requirements, as thats entirely the purpose of my Macbook Pro