That transition is so effective! Note how the piano comes in on the second tune ("Lady Anne Montgomery") without crashing. In the second tune, she never resolves the B part until the very end of the tune. A textbook example? She wrote the book with this recording!
Every bass line in the first jig ("Seven Stars") is elegantly constructed, moving somewhere without overpowering the fiddle. Note especially at 1:10 how she adds volume as the bass line drives toward the top of the tune.
The piano plays the first jig with mostly downbeats, the light touch with sustain creating an airy mood. The second tune's more percussive boom-chuck creates a sense of greater urgency. In the final tune ("Salvation"), Mary Cay powers in with her characteristic drama, using a whole range of tension-building techniques: pedal points, that suspended (four) chord, finally breaking into a solid descending scale.
(This album well illustrates how to play piano in a larger rhythm section. The guitar provides a sharp offbeat; the bass announces an underlying chord foundation; her piano provides rhythm, moving bass lines, and melodic tension all within that framework.)
The first tune is liquid gold, not a contra tune at all but so pretty. The last tune ("The Bonxie") has Mary Cay closing with that characteristic suspended chord downbeats on top of a pedal point, breaking out of it with a spectacular sequence of dramatic, crashing chords. You need not only the drone to build tension, but also some way to resolve it effectively.
The introduction doesn't much sound like contra dance music; but the tune ("Cattle in the Cane") launches after about a minute. Peter starts out with straight backup, then takes off on a splashy solo, then hunkers back down to the plain backup style again. (Do you like solo piano in contra dancing?)
Another piano in a big band and a powerhouse minor key tune ("Tam Lin"). Listen to all the different moods she strikes -- that eerie treble is just two chords! -- and how she never resolves until the top of the phrase. The banjo is playing with a heavy downbeat, which the piano accentuates. Hotpoint always achieves that sense of perpetually rolling forward; and they always get whoops.
Hear how the opening four-beat balances in A1 and A2 are consistently punctuated, and how the forward-and-back in B2 is pounded on the fourth beat only. In the second tune ("Strawstack"), note how the B part returns over and over to the same theme of building up to the A1 balance. Simple chord progressions (that never resolve) over a simple rocking left hand; long crescendos; four-beat block chords to end the phrase; and even an ever-so-slight ritard before the crash on A1.
A textbook example of how to play for contra dances. They start off with a solo mandolin melody (and the caller can be heard!). They don't add to it until the next time through the tune ("Jeff Davis"). Each effect is held through an entire tune. The fiddler consistently hammers on those end-of-phrase hanging fifths. The guitar mostly plays a (necessarily light) downbeat and a chunked offbeat, but occasionally provides a full chord on the downstroke for emphasis, just like a piano's block chord. The mandolin alternates between melodies and its own chunking. The dancers provide a downbeat with their feet. All that excitement -- and no piano!