I don't know anything about the 'FlexBeam' red light device, but some of the advertisements for red light devices make me think of Al Capp's Shmoo.

Below is a sample of my experiments with Red Light and Near Infrared Light, (NIR), therapy. They include steady burning, pulsed, and pulsed on top of steady burning. The pulses are square waves with a frequency of about A above middle C.
I built all the devices that I used. Simple circuits. Components are run of the mill.

1. A single pulsed NIR LED, (Liteon HSDL-4261: Wavelength 870 nM) driven by a 2N3904 transistor and an LM555 Integrated Circuit, (IC) pulser. Built from materials on hand. It operates on batteries. LED input power: .07 Watts. Coverage area: .03 square inches.

A toothache, treated by direct contact to the gum for five minutes, faded after about half an hour. Success? Coincidence? Placebo effect? Wishful thinking conveyed to the subconscious mind? Toothaches do come and go. It “worked” every time for subsequent routine toothaches but it didn't do anything at all for a tooth with a broken root.

2. A 4 by 6 array of pulsed RED LEDs, (Lumimax LED-5RED: Wavelength 625 nM), driven by a 2N1711 transistor and an LM555 IC pulser. The array was built by replacing the white LEDs in a rectangular flashlight with red ones and altering the wiring as needed. The flashlight's power button was rewired to turn the pulse circuit on and off. It is powered by a 5.9 Volt AC adapter that began life as a cell phone charger. Array input power: .55 Watts. Coverage area: 2.4 square inches.

This device, regardless of time used up to 30 minutes, had no noticeable effect on age spots or hair but eased, and often entirely stopped, the pain of a small inguinal hernia. The hernia also flares up less now. When placed directly on the area to be
treated the distance from skin to LED is about half an inch.

3. A 3 by 3 array of NIR LEDs mounted on a small piece of perf board and housed in a plumbing item that was intended to cap a ¾ inch PVC pipe. An extension was added to set the distance from LEDs to skin at the point where the lights converged. Coverage area: .44 square inches.

Driver: LM555 pulser, LM324 buffer, 2N3055 transistor, switched ballast resistors allow 10 different power levels. Connectors allow a variety of treatment heads and power supplies to be used. Array input power this experiment: 1.98 Watts.

Effective but slow in treating age spots. Rough textured spots most stubborn. Somewhat better results with dry skin patches. Some hair revived at some sites, not enough to get excited about. Lightening of skin around spots. Some wrinkle reduction. Relieved the pain of a fire ant bite after five minutes treatment. Pain came back a few hours later.

4. A circular array of three rings mounted through holes drilled into a short length of 1.5 inch PVC pipe. Reminds one of a corncob. The treatment area is inside but there is some outside scatter. The first and third rings are made up of 10 REDs, The second ring is made up of 12 NIRs. The RED segments are four LEDs in series with the segments in parallel. The NIR segments are six LEDs in series with the segments in parallel. Then the RED and NIR rings are paralleled. Without this arrangement two drivers would be needed because the REDs operate at 2.2 Volts and the NIRs operate at 1.4 Volts. Same driver as number 3. Had to buy some more LEDs.

Used around first finger right hand for joint pain. Pain went away, hasn't come back. Coverage area: 3.75 square inches.

Used around right thumb for splitting nail. Nail started growing normally. At cuticle the nail began growing out smoother. Skin under the nail lightened in places. Coverage area: 3.75 square inches.

Used around first finger left hand for a long standing numbness caused by a deep cut of 20 odd years ago. No relief, but a fresh superficial cut on the same finger healed with remarkable speed. Coverage area: 3.75 square inches.

Used on big toes for pain that I supposed to be gout. Pain was gone the next day. Coverage area: 7 square inches. Half of the nail on the adjacent toe of the left foot broke off two days later. Amazing strange. It grew back normally.

5. A flat five by thirteen array mounted in a length of four inch PVC pipe. An arm or a foot can be inserted. The distance from the array to the skin, and thus the coverage area, varies according to the limb and which portion of which limb it is used on. Same driver as number three. Radiation area: 5.8 square inches.

Used on feet for tingling and numbness. Seems to help somewhat. Little or no tingling sitting barefoot in a recliner. Still some numbness while walking.

Used on right hand and wrist. Lightness in skin. Shrinking of age spots continues. A little wrinkle reduction.

Used on left forearm. About the same as right hand and wrist.

RED/NIR therapy seems to be working to some degree for some of the things that I have tried. “Once is happenstance, twice is coincidence, after three it's a trend.”