Google for information about "html relative link vs absolute link". There's plenty of information available on the web about this topic. You need to learn more about HTML if this area is unfamiliar to you.
If you upload your content to any internet web server, it is being served over HTTP. If you look at the very beginning of the address in your web browser, you will usually see HTTP:// or HTTPS:// This indicates the content is coming from a web server location on the internet. So upload your content to a website, or if it's intended for an LMS, upload it to SCORM Cloud to test. Both will be HTTP.
Copying that same content to a folder on your LAN drive or local PC hard drive will NOT have the same result and your Captivate content will quite possibly NOT work because of an issue known as Flash Global Security (read the link above I provided).