If you are on a mobile device such a an iPad, the standard view doesn't allow for scrolling horizontally.

I'm guessing it uses Flash or something like that.

Makes sense. On my new tablet.

so what do you do then? Like how can you move on the tablet?

On my iPod Touch, I just see all the posts, for plurk, in a column. If I want to see who responded to my posts, I just click a tab.

Here's a screenshot of plurk

Yeah, I see what you mean. I see in "standard view", I can't scroll horizontally, either.

I do more plurk-reading, when I'm at my desktop computer.