Ignorance and callousness are not virtues
I don't know what that error means, specifically.
If you want to try uninstalling and reinstalling the script (and greasemonkey, if appropriate), it might help, or you may need to manually remove the script before reinstalling. There are instructions for doing that all through this forum, but if you need it I will repost them.
Since your streaming is working fine, why don't you just shut your script off when you want to download and do as fatty suggested: To download (without the script) now, you need to COPY the link, OPEN A NEW TAB, then PASTE the link into the new tab, or it won't work.
A bleeding heart is a symbol of holiness, a symbol of compassion, not an epithet
When our discourse sinks to the level of meaningless, pejorative labels and personal name-calling rather than honest reflection and reasoned dialogue, we are no longer a people, but a mob