If you look at VideoViewer sample, you will see how to record video from cameras. In the sample, there are start and stop recording buttons so it might be helpful.
https://doc.developer.milestonesys.com/html/index.html?base=samples/componentsamples/videoviewer/readme.html&tree=tree_2.html
If you want to see camera’s status, please explore Status Viewer sample. This sample might be helpful –
https://doc.developer.milestonesys.com/html/index.html?base=samples/componentsamples/statusviewer/readme.html&tree=tree_2.html