Whether it's a good practice depends on your business goals.
Many people will not fill out such a form unless they're convinced the video is incredibly useful. If you want the maximum number of people to SEE the video, don't use the form.
On the other hand, when you just post the video without a form, you don't collect any contact information from your site visitors. Even if you ask them at the end of the video to fill out the form to receive more information, the majority will not do so.
So, if you want to collect contact info from everyone who views the video and don't mind that most who visit your site will opt to not view the video, use the form. If you want the most people possible to view the video and don't mind missing getting the contact info for many of them, then don't use the form.
As I said, there is not no definite "best practice." What is best for your site depends on your business goals and business model.