function unlockGoogleVideo(url) {
        if (Config.VIDEO_PROXY_SERVER_HOST && isGoogleVideoUrl(url)) {
            if (isGoogleVideoUnlockRequired(url, getLastProxiedGoogleVideoId())) {
                return proxy.getGoogleVideoUrl(url);
            }
        }
    }
If the account proxy was used to retrieve the video info, the following applies:
some video files (mostly music videos) can only be accessed from IPs in the same country as the innertube api request (/youtubei/v1/player) was made.
to get around this, the googlevideo URL will be replaced with a web-proxy URL in the same country (US).
this is only required if the "gcr=[countrycode]" flag is set in the googlevideo-url...
@returns The rewitten url (if a proxy is required)