If you wish, you are able to manually mix between songs using the OtsAV Software Mixer. For details on the OtsAV Mixer click here. Below is a very basic example of how you can manually mix.
Disable the Auto
DJ feature by clicking on the 
icon on the toolbar
(or pressing Ctrl+D on your keyboard).
When Deck A is playing select the track you wish to mix into on Deck B.
Find the point in the track you want to mix into; you can use the Frame Seek feature to help you set the exact cue point.
Set the cue point using the Ctrl + F6 keys. For detailed keyboard shortcuts click here.
Note: OtsAV has pitch and tempo adjustments. These adjustments can be used to match the timing of the current playing song. You can use the Pitch/Tempo bending feature to help you keep in time. For details click here.
At the right time press the F6 key to begin Deck B playing. You may need to alter the Pitch or Tempo or use the Pitch/Tempo bending feature to keep the song in time.
When you wish to fade to listen solely to Deck B, press one of the X-Fader keys, e.g. Number 3 on your numeric keypad. Click here for X-Fader hot keys.
If your Ots files have BPM
values, either manually entered or from the Ots file's Beat Info (active
or not), the calculated BPM of your songs can be used to Match the BPM
between decks. Pressing the 
on the non-playing deck will
the match the BPM of that song, to the playing song in the other (playing)
deck.
Tip: To learn more about the art of beat mixing, take a look at the Automated Beat Mixing Tutorial.