XVID:
685MB < xvid size < 702MB
702265KB < xvid size < 719694KB (windows explorer viewed size)
719119885 bytes < xvid size < 736966656 bytes
max = 736,966,656 bytes (719694 KB )(702 MB)
minimum = 713,031,680 bytes (696320 KB )(680 MB)

txd2k5 states:

- Release runtime must be at least 50 minutes for using the full burnable 
  media capacity. In such cases, releases MUST utilize a MINIMUM of       
  680mb of the 700mb standard burnable media (Multi-CD releases MUST      
  conform to the 680mb minimum, for each CD used). Any other use of the   
  media shall not be over 350mb (Sizes between 350mb to 680mb are not     
  allowed).                                                               


txd2k9 states:

- MAXIMUM CD media capacity value is 736966656 bytes = 719694 KB = 702 MB
- MINIMUM CD media capacity value is 723517440 bytes = 706560 KB = 690 MB

http://rules.nukenet.info/t.html?id=2005_XViD.nfo
http://rules.nukenet.info/t.html?id=2009_XViD.nfo
http://en.wikipedia.org/wiki/CD-ROM#Capacity
_______________________________________________________________________________

DVDR:
4,718,592,000 Bytes
4,608,000 KB
4,500 MB
4.395 GB

wikipedia claims:
DVD-R = 4,707,319,808 Bytes
DVD+R = 4,700,372,992 Bytes
DVD-R DL = 8,543,666,176 Bytes
DVD+R DL = 8,547,991,552 Bytes

^^^ old. new( tdrx2k9 ):

4,700,372,992 bytes
-> http://rules.nukenet.info/n.html?id=2009_DVDR.nfo

http://rules.nukenet.info/t.html?id=2005_DVDR.nfo
http://en.wikipedia.org/wiki/DVDR#Recordable_DVD_capacity_comparison
_______________________________________________________________________________

BDr:

TBDR2K9 States:

between 22888 MB and 23866 MB unless source is BDR25

Single Layer: 23841.86MB
Dual Layer  : ?

Wikipedia claims:
25 GB (23.28 GiB)
50 GB (46.57 GiB)

http://rules.nukenet.info/t.html?id=2009_BDr.nfo
http://en.wikipedia.org/wiki/Bluray
http://www.avsforum.com/avs-vb/showthread.php?p=16169482
http://en.wikipedia.org/wiki/GiB
_______________________________________________________________________________

X264:

 5.1)  Final mkv file size in MiB (1048576 bytes) must be:
           Multiples of 2240
           DVD5/x (1493, 1120, etc.)
           8140, 2713
           In addition, 3360 and 4070 are allowed for 1080p tv.
 5.2)  A max undersize of 40 MiB can be tolerated.

minimum acceptable filesizes:
367    ( 407   - 40 )
408    ( 448   - 40 )
457    ( 497   - 40 )
520    ( 560   - 40 )
300    ( 640   - 40 )
706    ( 746   - 40 )
856    ( 896   - 40 )
1080   ( 1120  - 40 )
1453   ( 1493  - 40 )
2200   ( 2240  - 40 )
2673   ( 2713  - 40 )
4440   ( 4480  - 40 )
6680   ( 6720  - 40 )
8100   ( 8140  - 40 )
8920   ( 8960  - 40 )
11160  ( 11200 - 40 )
13400  ( 13440 - 40 )
15640  ( 15680 - 40 )
17880  ( 17920 - 40 )
20120  ( 20160 - 40 )
etc etc. 

http://rules.nukenet.info/t.html?id=2008_X264-2.nfo
http://rules.nukenet.info/x3Zw326.png