Technically, the restrictions on TV ads born of regulation mean that the ads are uniform in length and open to censor if they contain inappropriate material.
I’d also argue that currently TV ads are watched in a different environment than online video; although this is changing as online TV becomes more prevalent.
TV is generally watched passively and often in a relaxed environment, whereas online video is interactive and the viewer easily distracted by other content.
So does this affect the way that video is made for the two mediums? Yes. TV ads are not necessarily the best way to grab a busy, information-hungry, web-user.
As the Internet matures and the ways we consume its content diversify via mobile, we’re still learning how to fashion the all important messages we want to push through the vast amounts of competing information on the web.