Yes I try to make my uploads 20MB - 30MB with an acceptable quality as my uploads speed is only 20kbps. It really takes a really long time for me to upload even a 10MB video.
Oh I see, that's too bad yeah :<
If there's a place you can go to to leech some free and fast internet for uploading, you wouldn't have to worry too much about filesize. Though I haven't been able to make videos recently, I've uploaded at my university since my home internet sucks too (40 Kbps upload max), whereas at my uni a 350 MB file can be uploaded in less than 5 minutes.
For your final advertisement cut, I recommend a high bitrate and either upload overnight (at your upload speeds 300 MB will take about 7 hours), or find another place to upload. I realize you're under bandwidth constraints, and I mean no offense, but to use an analogy, imagine a paper advertisement that's been folded or scrunched up; people would pay less attention to it, even if the advertisement itself was really well made. You can always render a smaller sized version for us to check and offer suggestions to, but for your absolute final video, maybe render above Youtube bitrates at the very least?