For some of you that may also of had some failing rtmp links.
You have to add flashVer before swfUrl, you also have to replace spaces with \20 so
flashVer=WIN 22,0,0,209
becomes
flashVer=WIN\2022,0,0,209
some small oddity to do with librtmp vs rtmpdump
https://rtmpdump.mplayerhq.hu/librtmp.3.html
Quote:Additional options may be specified by appending space-separated key=value pairs to the URL. Special characters in values may need to be escaped to prevent misinterpretation by the option parser. The escape encoding uses a backslash followed by two hexadecimal digits representing the ASCII value of the character. E.g., spaces must be escaped as \20 and backslashes must be escaped as \5c.