Film on water is probably protien build up from your water supply if it is like an "oily sheen". Bubbles could be the same or a bubble nest. Did you get the shrimp and betta all at once? If so get an ammonia test kit and change out 50% water (conditioned water)evry other day until you get the ammonia test kit. I recomend the API brand sold at most pet supplies.

Thank you woeisme for the advice. I'll get the ammoia test kit this weekend. I changed out 1/3 of the water yesterday with conditioned water. We did get the shrimp and betta at the same time.
Denise

you can usually bring a little of your water to your fish or pet store and most places will check your water there.

A filter that gives lots of flow helps and maybe a papaer towel to soak up what is on the surface may remove some of it.