Why does my MyBook HDD fail to download files?

Hello,

What i wanted to do. I have a Time Capsule, connect a external HDD to it, download some movies, and watch it on my Macbook, wireless.

Funny enough it does not work. The HDD can download 1 movie for example, not fast but it runs, when i'm adding a second movie to download the HDD stops and the download program jams. I have to reboot MacBook completely.

I can open previous movies and i can watch them (wireless), but downloading seems to be a problem.

I run the downloading program from the MacBook, from here it goes wireless to the TC.

Is the wireless part a problem? Is the HDD the problem?

The HDD is Mac formatted.

When connecting HDD direct on MacBook no problem at al.

I'm lost. Can you guys help me?

Thanks.