Use Interlace to connect the odd and even scanlines of a clip.
To access the Interlace menu:
Timeline, then use ConnectFX (see Creating ConnectFX).
Tools, then select from the menu (See Accessing Tools).
The Interlace node accepts a front clip as input, and outputs a result.
For each pair of frames in the input clip, the Field 1 scanlines of one frame are interlaced with the even scanlines of the second frame to produce a single frame in the generated clip.