You of course, however you must grant certain rights to Youtube and other users in exchange for the use of the platform .
See below Youtube Terms of Service;
Licence to YouTube :By providing Content to the Service, you grant to YouTube a worldwide, non-exclusive, royalty-free, transferable, sub licensable licence to use that Content (including to reproduce, distribute, modify, display and perform it) for the purpose of operating, promoting, and improving the Service.
Licence to Other Users :You also grant each other user of the Service a worldwide, non-exclusive, royalty-free licence to access your Content through the Service, and to use that Content (including to reproduce, distribute, modify, display, and perform it) only as enabled by a feature of the Service.
Duration of Licence
The licences granted by you continue until the Content is removed.
How does this apply to Facebook,Twitter,Instagram and other Social Media platforms. It is key to read the tiny prints of Terms and Condition(T&C) ? How does Copyright operate in view of these Terms of Service or T& Cs What is your view ?