The MPlay file open dialog has extra controls for opening image sequences:
Lock Image Size
Selecting sequences does not overwrite the custom image size fields (Image Size ▸ Custom). Normally the fields automatically update with the resolution of the selected sequence.
Frame Range and Step
The frame range and frame step to load from a sequence. You can use this to load a subrange of a sequence, and/or every ‹n›th frame, to save space.
Lock Frame Range
The Frame Range fields do automatically update when you select a sequence.
Frame Rate
Frame rate of the selected sequence. The initial value is Houdini’s global frame rate.
Flip Image Vertically
Flips loaded images vertically.
Allow Caching of This Sequence
Caches the sequence for quicker playback.