2 bugs

[YouXam]

fix bug: extra command attributes

Extra command did not have name and desc attributes.

fix bug: video cannot be received

We don't seem to need either file or path to exist at the same time. In fact, some slaves have only one attribute, file.

[YouXam]

In fact, at the time I submitted this pr, I had only completed the first two commits. The later commits are in fact just modifications based on my own usage habits. I did not know that the new commits would be merged into the previous pr after the pr was submitted.