Most Wifi Upload Speeds Are Probably Less Than 5Mbps
It looks like most terrestrial ISPs in Bali are using legacy copper (ie. repurposed telephone and coaxial TV cables). The highest upload speed you'll achieve at any single site served by legacy copper is most likely limited to 5Mbps. The 5 Mbps upload speed limitation is inherent to most legacy copper networks because their bandwidth is rather limited and ISPs allocate much more spectrum to download than upload. I have found a few exceptions where coax cable provided up to 15Mbps upload, but that seems to be very rare.
In my travels I have found that the vast majority of wifi hotspots are served by legacy copper (you can infer as much rather easily with the right network tools). While I have never traveled to Bali, I don't see why the situation would be any different there.
How Long Will the "6Gb" Upload Take?
I assume you you need to upload 6 gigabytes of data (as opposed to gigabits).
If you were able to find a hotspot where you could use the full 5Mbps upload bandwidth, the 6 GB of data you need to upload would take about 3 hours). That's best case scenario. I would expect it to take 4x to 10x that long because you'll probably experience network congestion or QoS that reduces your upload speeds. So you're looking at maybe a half GB upload per hour if you are sort of lucky.
MetroNET seems to be an ISP in Bali that uses fibre. Fibre, in general, does not wind up with an inherent upload speed limit the way legacy copper does. I would try to find a hotspot served by this network for there is at least a hope of achieving the upload speeds to get your images and video out. Even if the site has a fibre connection, your connection might still be throttled so you'll still have to do some testing to be sure.
Ookla Speed Test is Your Friend
I generally run Ookla's speed test on any network I might need to use while traveling. I find bandwidth to always be a struggle when traveling, so I like to know early what speed networks are available.
Your best bet may be a local LTE SIM card. I regularly achieve 20 Mbps upload speeds over LTE when traveling. That would bring your 6 GB upload down below an hour. You'll have to be near a good cell tower and consider bandwidth caps, but it might be your only practical solution.
This solution is kind of a moving target because it depends on finding a network operator that offers reasonably-priced prepaid short-term data plans. So far I have found that the availability of such plans for any given network operator changes from time to time (at least in North America and Europe). I tried to determine if one of the Indonesian operators offer such a plan without success (I can't read Indonesian).