"Por defecto" is very common; "Por omisión" is used by KDE translation team; "predeterminado" may also be used. See https://es.wikipedia.org/wiki/Valor_por_defecto
While the anglicism "screencast" or the Spanish "videografía" could be used (see https://es.wikipedia.org/wiki/Screencast), they risk not being widely understood. I suggest the longer but explicit "grabación de pantalla"
If "tema" may one day cause confusion with "topic"'s translation "tema", we may want to change "topic"'s translation to "tópico" or "asunto"