Media diagnostics · Primary-source explanation; examples are illustrative. Instructions are based on publisher guidance; a UK IPTV account was not tested on this platform.
Follow the preview reference lifetime
A browser page can create an object URL for a locally selected media object and give that reference to a preview. MDN describes revokeObjectURL as releasing a previously created object URL and advises doing so after use has finished. If the application revokes immediately while another control still relies on the reference, a later preview or open action may have no valid object URL to use. This is a lifecycle problem to investigate before blaming the file format.
Test the actual sequence of actions
For an original local exercise, select a harmless short clip, preview it, switch to another clip, then try the application next action. Record whether that action uses the first or second reference. Keep cleanup paired with the specific reference it releases. A single global variable which is overwritten during a transition can make it difficult to tell which preview has been retired. The exercise checks the application own state; it does not require transmitting the file.
Describe cleanup accurately
Releasing an object URL tells the browser it need not retain that reference. It is not a command to erase the original file from the computer. Repeating the call for an already released or invalid reference has no effect according to the documentation. Do not show a user message claiming permanent deletion merely because cleanup ran. Check that previews still needed by the page remain usable, while obsolete references are released when their consumers have finished.