This video is called Transitional Fossil: Fish to Amphibians.
From ABC News in the USA:
Fossil of most primitive 4-legged creature found in Latvia; lived eons before dinosaurs
By SETH BORENSTEIN AP Science Writer
WASHINGTON June 25, 2008
Scientists unearthed a skull of the most primitive four-legged creature in Earth’s history, which should help them better understand the evolution of fish to advanced animals that walk on land.
The 365 million-year-old fossil skull, shoulders and part of the pelvis of the water-dweller, Ventastega curonica, were found in Latvia, researchers report in a study published in Thursday’s issue of the journal Nature. Even though Ventastega is likely an evolutionary dead-end, the finding sheds new details on the evolutionary transition from fish to tetrapods. Tetrapods are animals with four limbs and include such descendants as amphibians, birds and mammals.
While an earlier discovery found a slightly older animal that was more fish than tetrapod, Ventastega is more tetrapod than fish. The fierce-looking creature probably swam through shallow brackish waters, measured about three or four feet long and ate other fish. It likely had stubby limbs with an unknown number of digits, scientists said.
According to Jennifer Clack, a paleontologist at the University of Cambridge who has studied the fossils of these extinct creatures for more than two decades, the earliest land vertebrates — also known as tetrapods — were more diverse than we could possibly imagine: here.