Do you really think a 50GB BD .iso would play on a Pentium 4? No. What about a 20GB 20MB/s rip. Nope. That 64 wouldn't help either. The old Pentium 4's belong in the tip. They are just useless in 2012.
You're misinformed. Of course it would run HD videos with a proper graphics card for the job. After all, it's the graphics card that plays the video, not the CPU.
Also, you've mixed up 1 zero. It's 2 MB/s, not 20 MB/s.