They are electric fireflies. They actually look pretty realistic. I have people amazed that I have so many fireflies in my yard and they are virtually non existent here. These run on 12v DC powered from the shed on a wall wart. (class II).
Firefox has a security setting that requires https in all windows, but there is an option setting to turn that off which would allow http (there is also an option setting to require https only in private browsing mode). Https is probably the default setting.
I have Firefox and Slim Jet. Both are OK with HTTP. I am surprised you are not having trouble with other sites. There are plenty of HTTP sites out there although I see this is HTTPS. I will oook at my web host info and see what I have to do to "secure" my site. I also manage one for the HOA. Maybe that is why we don't get as much traffic as I suspect but nobody has said anything yet.
I don't know exact reasons why the pictures aren't showing up, they did in the past, I figured it had something to do with an automatic Browser update (?) , but maybe it's got something to do with something being referenced on this site with the [img] tags, or coming from an https site??
I changed this site to https a couple years back because one of the Browsers was giving me a warning the site was not secure or that it would soon be reported as such in future Browser updates.
FYI, I can go directly to your site and see the pictures in my browsers, It just gives me a Not Secure warning next to the address bar. If you do go to https the [img] links may have to be changed to get the pictures displayed here. If that's the case I can help with that.