So using Windows Media Player I'm trying to burn some cassette tapes that I've digitized onto CDs as an "Audio CD", but when I try to, it tells me the file is "too large." The file is less than 700MB but it refuses to work because it's technically longer than 80 minutes. Is there any way I can get around this restriction?
No there is no way around it. If it is an 80 minute disc then 80 minutes is the farthest you can go. If you want to put more files on then you can burn a data CD with audio files on it, but then you can not play it in all CD players. You would need a CD player that can play audio files from a data CD.
Technically longer? If you're over by just a few seconds you might want to try loading the songs into a program and trim them up. Perhaps if you cut out some long fade outs or remove any dead space on the files you can get it down to 80min. If however you're at 84min, this won't work. Two CDs?
Some burning programs will allow you to "overburn" cds. Allowing more than the max rated length or space. It all depends what kind of cd burner and cd blanks are being used. But I have gotten about an extra 2 minutes onto a CD. Its really hit or miss though.
The program I use is Nero.
Try some of the free CD burner programs and see if they will let you "overburn". Your burner may or may not support this. You might be able to get an extra 2 minutes on there. I have not done this in many years so you will have to do the research to see what is possible these days.