Eureka is a US Science Fiction Drama/Comedy.
The town called Eureka is inhabited by mainly brilliant scientists who work on secret government projects.

The town is come across by U.S Marshall Jack Carter while he is transporting a fugitive back to jail
When an experiment goes wrong and kills the local Sheriff, Jack Carter is quickly found to be the best person for the job.
His work in the town and the way he connects with the people are what inveitably saves Eureka and (of course!) the world from one disaster after another.

The main sites link to videos of Eureka

Televisiononlineinfo.com
Sidereel.com
Yidio.com

The specific sites that stream episodes of are:
watcheurekaonline.com

You can also watch on Itunes the link for this is:

You can also watch on Amazon the link for this show is:
Eureka - Amazon