You can disable the capture  to JPEG button  by default. and when the video
play is pressed  or when the video  starts playing then you can enable the button.
You can achieve the same by keeping a boolean variable and keeping its value
to true when the video is running or else false.
You can capture picture  from the panel without using the coordinates. Just
write a method  in the panel itself that returns the image  object. In this way
you are not worried about the panel's coordinates