Keep in mind a 4.7 GB DVD-R holds about 4.36 - 4.37 GB of data, not 4.7.
(similar to how a hard disk drive of 500 GB does not hold that amount in practice. It's due to different way of describing data capacities.)
As lengoldstein suggested, you can choose a lower transcode setting if you are getting a too large error message. Also, if any of the audio files are PCM, choose to remove them. There will no doubt be AC3/DTS/MPeg audio alternatives.
Depends on 'what' you are trying to burn.
I get the impression your transcode settings are too high. Either video or audio transcode settings & that is why you are getting such an error message.
For audio: Dolby AC3 192-256 should be fine for most videos. Music videos or hi-fi fx movies you may wish a higher audio bitrate. (Also depends on the audio quality trancode of the video you have ... no point choosing a 448 kbps setting if it was encoded at 256 (or less) or equivalent in the particular audio format it came in.
)
For video (VBR/Variable Bit Rate): do not set the Maximum bitrate too high. 8.5 or below if your audio bitrate is 448 kbps or lower (7.5-8) or lower for safety). Average bitrate depends on length of video. Usually below 8, & for a 4.7 GB disk probably 5 or less for a 2 hr video. More like around 4-4.5 mbps.
If the file you have is a single video file & not a dvd TS folder, then ... One possibility is you convert the video to a lossless format that Nero recognises well. Then use that to burn with. (I made this suggestion because a few years ago I recall I had a similar issue with a particular video format with Nero ... Nero seemed to have problems knowing the final size of that video format. I think I just burnt anyway regardless of the error messages just like you received .. too long ago to remember lol)
Your problem might also be due to older version codecs that Nero uses that need updating (as my last paragraph suggested in part.)
Check for updates.
If you have DVD-RW disks, then trial out on one of those first.