  Photometric instabilities of $\beta$ Lyr were observed in 2016 by two
red-filter BRITE satellites over more than 10 revolutions of the binary, with
$\sim$100-minute sampling. Analysis of the time series shows that flares or
fading events take place typically 3 to 5 times per binary orbit. The
amplitudes of the disturbances (relative to the mean light curve, in units of
the maximum out-of-eclipse light-flux, f.u.) are characterized by a Gaussian
distribution with $\sigma=0.0130\pm0.0004$ f.u. Most of the disturbances appear
to be random, with a tendency to remain for one or a few orbital revolutions,
sometimes changing from brightening to fading or the reverse. Phases just
preceding the center of the deeper eclipse showed the most scatter while phases
around secondary eclipse were the quietest. This implies that the invisible
companion is the most likely source of the instabilities. Wavelet transform
analysis showed domination of the variability scales at phase intervals
$0.05-0.3$ (0.65--4 d), with the shorter (longer) scales dominating in numbers
(variability power) in this range. The series can be well described as a
stochastic Gaussian process with the signal at short timescales showing a
slightly stronger correlation than red noise. The signal de-correlation
timescale $\tau=(0.068\pm0.018)$ in phase or $(0.88\pm0.23)$~d appears to
follow the same dependence on the accretor mass as that observed for AGN and
QSO masses 5--9 orders of magnitude larger than the $\beta$~Lyr torus-hidden
component.
